研究者データベース

研究者情報

マスター

アカウント(マスター)

  • 氏名

    日髙 宏之(ヒダカ ヒロユキ), ヒダカ ヒロユキ

所属(マスター)

  • 理学研究院 物理学部門 凝縮系物理学分野

所属(マスター)

  • 理学研究院 物理学部門 凝縮系物理学分野

独自項目

syllabus

  • 2021, 磁性物理学, Magnetism, 修士課程, 理学院, 高圧・強磁場・極低温・物性実験
  • 2021, 物理学実験Ⅰ, Laboratory Exercise in Physics I, 学士課程, 理学部, 基本物性測定:磁化、比熱、電気伝導度、ホール効果、超伝導
  • 2021, 物理学実験Ⅰ, Laboratory Exercise in Physics I, 学士課程, 理学部
  • 2021, 物理学実験Ⅱ, Laboratory Exercise in Physics II, 学士課程, 理学部, 光の回折・干渉、レーザー、結晶構造、X線構造解析
  • 2021, 物理学実験Ⅱ, Laboratory Exercise in Physics II, 学士課程, 理学部
  • 2021, 物理学実験Ⅲ, Laboratory Exercise in Physics III, 学士課程, 理学部, 走査電子顕微鏡(SEM)
  • 2021, 物理学実験Ⅳ, Laboratory Exercise in Physics IV, 学士課程, 理学部, オームの法則、キルヒホッフの法則、テブナンの定理、受動素子と能動素子、 インピーダンス、テスター、オシロスコープ、ダイオード、トランジスタ、FET、 オペアンプ、特性曲線、増幅回路、演算回路 複素インピーダンス、複素アドミッタンス、伝送線、特性インピーダンス インピーダンス整合、誘電体、誘電率
  • 2021, 物理学実験Ⅲ, Laboratory Exercise in Physics III, 学士課程, 理学部

researchmap

プロフィール情報

学位

  • 理学博士(岡山大学)

プロフィール情報

  • 日高, ヒダカ
  • 宏之, ヒロユキ
  • ID各種

    201301013476285858

対象リソース

業績リスト

研究キーワード

  • 多極子秩序   複合極限(高圧・低温・強磁場)   低励起フォノン   カゴ状化合物   強相関f電子系   

研究分野

  • 自然科学一般 / 磁性、超伝導、強相関系

学歴

  • 1997年03月 - 2001年03月   大阪大学   基礎工学部

論文

  • Fusako Kon, Chihiro Tabata, Hiraku Saito, Taro Nakajima, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    Journal of the Physical Society of Japan 93 4 2024年04月15日
  • Ruo Hibino, Tatsuya Yanagisawa, Yoshito Mikami, Hiroyuki Hidaka, Hiroshi Amitsuka, Sergei Zherlitsyn, Joachim Wosnitza, Yu Yamane, Takahiro Onimaru
    Journal of the Physical Society of Japan 2023年07月15日
  • Keita Ushida, Tatsuya Yanagisawa, Ruo Hibino, Masato Matsuda, Hiroyuki Hidaka, Hiroshi Amitsuka, Georg Knebel, Jacques Flouquet, Dai Aoki
    Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 2023年05月22日
  • Ruo Hibino, Tatsuya Yanagisawa, Yoshito Mikami, Hiroyuki Hidaka, Hiroshi Amitsuka, Sergei Zherlitsyn, Joachim Wosnitza, Yu Yamane, Takahiro Onimaru
    Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 2023年05月22日
  • Hiroyuki Hidaka, Shun Yanagiya, Eikai Hayasaka, Yuma Kaneko, Tatsuya Yanagisawa, Hiroshi Tanida, Hiroshi Amitsuka
    Journal of the Physical Society of Japan 91 9 2022年09月15日
  • Hiroyuki Hidaka, Yoshihiko Ihara, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 90 9 2021年09月 [査読有り]
     
    9Be-NMR measurements were performed using single crystalline SmBe13 in order to investigate a magnetic structure of a low-temperature ordering state microscopically. We observed a spectral broadening in the ordered state, and the broadened spectral shape depends on the magnetic field directions. By comparing the experimentally obtained and simulated NMR spectra for magnetic fields along the cubic [001] and [011] directions, we argue a helical structure with a basal plane tilted from the (001) plane in low-field ordering region under the assumption of a helical with a propagation vector of (0, 0, 1/3) found in other RBe13 compounds (R = rare earths). Such a tilted helical structure is explained by a combination of an ellipse helical in the (001) plane and a longitudinal magnetic density wave along the [001] direction. Considering a magnetic easy axis parallel to [001] revealed by the magnetization measurements, the peculiar helical structure in SmBe13 may be built on delicate balance among exchange interactions, dipole-dipole interaction, and singleion magnetic anisotropy due to the crystalline electric field.
  • T. Yanagisawa, H. Matsumori, H. Saito, H. Hidaka, H. Amitsuka, S. Nakamura, S. Awaji, D. I. Gorbunov, S. Zherlitsyn, J. Wosnitza, K. Uhlířová, M. Vališka, V. Sechovský
    Physical Review Letters 126 15 2021年04月 [査読有り]
     
    We present acoustic signatures of the electric quadrupolar degrees of freedom in the honeycomb-layer compound UNi4B. The transverse ultrasonic mode C66 shows softening below 30 K both in the paramagnetic phase and antiferromagnetic phases down to ∼0.33 K. Furthermore, we traced magnetic field-temperature phase diagrams up to 30 T and observed a highly anisotropic elastic response within the honeycomb layer. These observations strongly suggest that Γ6(E2g) electric quadrupolar degrees of freedom in localized 5f2 (J=4) states are playing an important role in the magnetic toroidal dipole order and magnetic-field-induced phases of UNi4B, and evidence some of the U ions remain in the paramagnetic state even if the system undergoes magnetic toroidal ordering.
  • Hiroyuki Hidaka, Kota Mizuuchi, Eikai Hayasaka, Tatsuya Yanagisawa, Jun Ohara, Hiroshi Amitsuka
    PHYSICAL REVIEW B 102 17 2020年11月 [査読有り]
     
    The beryllide GdBe13 with the NaZn13-type face-centered-cubic structure has been known to undergo a proper helical-magnet ordering from experimental studies using polycrystalline samples. In the present study, we carried out electrical resistivity, specific heat, and magnetization measurements of single-crystalline GdBe13 in order to investigate a mechanism of its helical ordering. These measurements reveal that the present compound is a metallic system exhibiting the magnetic ordering of local Gd3+ moments at T-N = 24.8 K accompanied with strong magnetic fluctuations extending to temperatures well above T-N. Furthermore, we constructed a magnetic field-temperature (B-T) phase diagram for B parallel to [001]. It consists of a multidomain state, which is composed of magnetic structures with B applied parallel and perpendicular to the helical plane, in the lower-magnetic-field region below similar to 0.45 T and a possible single-domain conical one in the higher-field region in the ordering state. The helical structure of GdBe(13 )characterized by an incommensurate ordering vector q(0) of (0, 0, 0.285) is discussed on the basis of a competition of Heisenberg exchange interactions between the Gd3+ moments assuming an one-dimensional layer crystal. The sequential change in the exchange interactions determined by a mean-field (MF) calculation can be essentially understood by the Ruderman-Kittel-Kasuya-Yosida interaction via anisotropic Fermi surfaces, whereas the orientation of the magnetic moments will be determined by the dipole-dipole interaction. On the other hand, the MF theory predicts a much smaller critical field B-c than the experimentally obtained one. To discuss the deviation of B-c from the MF calculation, we show a possibility of a fluctuation-induced first-order transition.
  • Tatsuya Yanagisawa, Hiroyuki Hidaka, Hiroshi Amitsuka, Shintaro Nakamura, Satoshi Awaji, Elizabeth L. Green, Sergei Zherlitsyn, Joachim Wosnitza, Duygu Yazici, Benjamin D. White, M. Brian Maple
    PHILOSOPHICAL MAGAZINE 100 10 1268 - 1281 2020年05月 [査読有り][通常論文]
     
    In this study, ultrasonic measurements were performed on a single crystal of cubic PrNi$_2$Cd$_{20}$, down to a temperature of 0.02 K, to investigate the crystalline electric field ground state and search for possible phase transitions at low temperatures. The elastic constant $(C_{11}-C_{12})/2$, which is related to the $\Gamma_3$-symmetry quadrupolar response, exhibits the Curie-type softening at temperatures below $\sim$30 K, which indicates that the present system has a $\Gamma_3$ non-Kramers doublet ground state. A leveling-off of the elastic response appears below $\sim$0.1 K toward the lowest temperatures, which implies the presence of level splitting owing to a long-range order in a finite-volume fraction associated with $\Gamma_3$-symmetry multipoles. A magnetic field-temperature phase diagram of the present compound is constructed up to 28 T for $H \parallel$ [110]. A clear acoustic de Haas-van Alphen signal and a possible magnetic-field-induced phase transition at $H \sim$26 T are also detected by high-magnetic-field measurements.
  • Hiroyuki Hidaka, Kota Mizuuchi, Tatsuya Yanagisawa, Hiroshi Amitsuka
    Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019) 2020年03月19日 [査読有り]
  • Rare-Earth Atomic Motion in RBe13 (R: La, Pr, Sm)
    Satoshi Tsutsui, Yusei Shimizu, Hiroyuki Hidaka, Akinari Kohriki, Ryoya Murata, Yoshitaka Yoda, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JPS Conf. Proc 30 011115-1 - 011115-6 2020年03月19日 [査読有り][通常論文]
  • Satoru Hamamoto, Yuina Kanai-Nakata, Hidenori Fujiwara, Kentaro Kuga, Takayuki Kiss, Atsushi Higashiya, Atsushi Yamasaki, Shin Imada, Arata Tanaka, Kenji Tamasaku, Makina Yabashi, Tetsuya Ishikawa, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka, Akira Sekiyama
    Proceedings of J-Physics 2019: International Conference on Multipole Physics and Related Phenomena 2020年02月13日 [査読有り]
  • Tatsuya Yanagisawa, Hiroyuki Hidaka, Hiroshi Amitsuka, Sergei Zherlitsyn, Joachim Wosnitza, Yu Yamane, Takahiro Onimaru
    Proceedings of J-Physics 2019: International Conference on Multipole Physics and Related Phenomena 2020年02月13日 [査読有り]
  • S. Hamamoto, Y. Kanai, S. Fujioka, Y. Nakatani, H. Fujiwara, K. Kuga, T. Kiss, A. Higashiya, A. Yamasaki, S. Imada, A. Tanaka, K. Tamasaku, M. Yabashi, T. Ishikawa, H. Hidaka, T. Yanagisawa, H. Amitsuka, K. T. Matsumoto, T. Onimaru, T. Takabatake, A. Sekiyama
    Journal of Electron Spectroscopy and Related Phenomena 238 2020年01月 [査読有り]
     
    We report the core-level photoemission study of cubic PrBe13, PrIr2Zn20 and PrB6 using linearly polarized hard X-ray. We have successfully observed linear dichroism (LD) in Pr3+ 3d core-level photoemission spectra reflecting the 4f ground-state symmetry for all the compounds. The observed LDs and polarization-dependent spectra are reproduced by ionic-model calculations including the full multiplet theory and the local crystalline electric field (CEF) splitting. We have confirmed that LDs in Pr3+ 3d core-level photoemission spectra are able to determine unambiguously the Pr3+ 4f ground-state symmetry.
  • D. S. Christovam, C. Giles, L. Mendonca-Ferreira, J. Leaõ, W. Ratcliff, J. W. Lynn, S. Ramos, E. N. Hering, H. Hidaka, E. Baggio-Saitovich, Z. Fisk, P. G. Pagliuso, C. Adriano
    Physical Review B 100 16 2019年10月21日 [査読有り]
     
    The pressure evolution of the magnetic properties of the Ce2RhIn7.79Cd0.21 heavy fermion compound was investigated by single crystal neutron magnetic diffraction and electrical resistivity experiments under applied pressure. From the neutron magnetic diffraction data, up to P=0.6GPa, we found no changes in the magnetic structure or in the ordering temperature TN=4.8K. However, the increase of pressure induces an interesting spin rotation of the ordered antiferromagnetic moment of Ce2RhIn7.79Cd0.21 into the ab tetragonal plane. From the electrical resistivity measurements under pressure, we have mapped the evolution of TN and the maximum of the temperature dependent electrical resistivity (TMAX) as a function of the pressure (Pâ‰3.6GPa). To gain some insight into the microscopic origin of the observed spin rotation as a function of pressure, we have also analyzed some macroscopic magnetic susceptibility data at ambient pressure for pure and Cd-doped Ce2RhIn8 using a mean-field model including tetragonal crystalline electric field (CEF). The analysis indicates that these compounds have a Kramers doublet Γ7-type ground state, followed by a Γ7+ first excited state at Δ1∼80K and a Γ6 second excited state at Δ2∼270K for Ce2RhIn8 and Δ2∼250K for Ce2RhIn7.79Cd0.21. The evolution of the magnetic properties of Ce2RhIn8 as a function of Cd doping and the rotation of the direction of the ordered moment for the Ce2RhIn7.79Cd0.21 compound under pressure suggest important changes of the single ion anisotropy of Ce3+ induced by applying pressure and Cd doping in these systems. These changes are reflected in modifications in the CEF scheme that will ultimately affect the actual ground state of these compounds.
  • Evidence for the Single-Site Quadrupolar Kondo Effect in the Diluted non-Kramers System Y1-xPrxIr2Zn20
    T. Yanagisawa, Hiroyuki Hidaka, H. Amitsuka, S. Zherlitsyn, J. Wosnitza, Y. Yamane, T. Onimaru
    Physical Review Letters 123 067201  2019年08月 [査読有り][通常論文]
  • 柳澤達也, 三上義人, 日高宏之, 網塚浩, 中村慎太郎, 淡路智
    東北大学金属材料研究所強磁場超伝導材料研究センター年次報告 2018 92‐93  2019年06月 [査読無し][通常論文]
  • Hiroyuki Hidaka, Kota Mizuuchi, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 88 3 2019年03月 [査読有り][通常論文]
     
    Magnetic susceptibility, specific heat, and electrical resistivity measurements have been performed on single-crystal EuBe13 in the temperature range between 2 and 300 K to investigate its phonon property and the valence state of the Eu ion. The obtained temperature dependence of the magnetic susceptibility curves obey a typical Van Vleck susceptibility for Eu3+ with a nonmagnetic ground state in the entire measured temperature range. In the case of the specific heat, we observed the coexistence of Debye and Einstein phonon modes with characteristic Debye and Einstein temperatures of ~ 835 K and ~167 K, respectively, which are in good agreement with those previously reported for other isostructural MBe13 compounds (M = rare earths and actinides). The temperature dependence of the resistivity for EuBe13 shows an unusual T-cubed like dependence at low temperatures, as also observed for the nonmagnetic isostructural compound LaBe13, which can be reproduced well by calculations based on electron--phonon scattering using the estimated Debye temperature and Einstein temperature. We also summarized the relationship between the Eu-valence state and the free distance between the Eu ion and the first-nearest-neighbor atoms in several Eu-based cubic compounds, and argued that EuBe13 takes the Eu3+ state despite its larger free distance than other Eu3+ compounds.
  • Hall effect and resistivity in epitaxial MnSi thin films and nanostructures under ambient and high pressure
    D. Menzel, D. Schroeter, N. Steinki, S. Süllow, A. Fernandez-Scarioni, H. Schumacher, H. Okuyama, H. Hidaka, H. Amitsuka
    IEEE Transactions on Magnetics 55 1500204  2019年02月 [査読有り][通常論文]
  • Chihiro Tabata, Yoshihiko Ihara, Shogo Shimmura, Naoyuki Miura, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 87 11 114707  2018年11月 [査読有り][通常論文]
     
    The magnetically ordered phase of body-centered-tetragonal UAu2Si2 was explored through Si-29-NMR experiments on a magnetically oriented powder sample. The field-swept NMR spectra show asymmetric peak splitting in a magnetic field applied along the tetragonal [001] axis below the magnetic phase transition temperature, T-N = 20K. This splitting is well explained by the occurrence of a magnetic order with a propagation vector of k = (2/3, 0, 0) and magnetic moments pointing parallel to the [001] axis, providing collateral evidence for uncompensated (++-)-type antiferro-magnetic ordering with a spontaneous [001] magnetization component.
  • Klára Uhlířová, Naoyuki Miura, Vladimír Tkáč, Jan Prokleška, Maciej Chrobak, Zbigniew Tarnawski, Hiroyki Hidaka, Tatsuya Yanagisawa, Vladimír Sechovský, Hiroshi Amitsuka
    Physica B: Condensed Matter 536 516 - 518 2018年05月01日 [査読有り][通常論文]
     
    Single crystals of ThBe13 and LuBe13 have been prepared using aluminum flux method. The crystals structure of both compounds was confirmed to be cubic of the NaZn13-type with the lattice parameters a = 10.183(6) Å and a = 10.395(3) Å for LuBe13 and ThBe13, respectively. The low temperature measurements of electrical resistance and ac susceptibility have revealed a BCS-type of superconductivity in ThBe13 below Tc = 125 mK. LuBe13 has been found to be superconducting below Tc = 630 mK.
  • Hiroyuki Hidaka, Ryoma Nagata, Chihiro Tabata, Yusei Shimizu, Naoyuki Miura, Tatsuya Yanagisawa, Hiroshi Amitsuka
    Physical Review Materials 2018 2 5 2018年04月27日 [査読有り][通常論文]
     
    The beryllides MBe13 (M = rare earths and actinides) crystallize in a NaZn13-type cubic structure, which can be categorized as a cage-structured compound. In this study, powder X-ray diffraction measurements have been performed on LaBe13, SmBe13, and UBe13 in the temperature range between 7 and 300 K in order to investigate their crystallographic characteristics systematically. They keep the NaZn13-type cubic structure down to the lowest temperature. We estimated their Debye temperature to be 600 - 750 K from analyses of the temperature dependence of a lattice parameter, being in good agreement with the values reported previously. Rietveld refinements on the obtained powder patterns revealed that the M atom in the 8a site is located in an almost ideal snub cube formed by 24 Be atoms in the 96i site, whose caged structure is unchanged even at the low temperatures. In addition, it is argued from the temperature variation of an isotropic mean-square displacement parameter that the MBe13 compounds commonly have a low-energy phonon mode, which can be described by a model assuming an Einstein oscillation of the M atom with a characteristic temperature of ~ 160 K.
  • T. Yanagisawa, S. Mombetsu, H. Hidaka, H. Amitsuka, P. T. Cong, S. Yasin, S. Zherlitsyn, J. Wosnitza, K. Huang, N. Kanchanavatee, M. Janoschek, M. B. Maple, D. Aoki
    Physical Review B 97 15 2018年04月17日 [査読有り][通常論文]
     
    The elastic properties of URu2Si2 in the high magnetic field region above 40 T, over a wide temperature range from 1.5 to 120 K, were systematically investigated by means of high-frequency ultrasonic measurements. The investigation was performed at high magnetic fields to better investigate the innate bare 5f-electron properties, since the unidentified electronic thermodynamic phase of unknown origin, the so-called "hidden order" (HO), and associated hybridization of conduction and f electrons (c-f hybridization) are suppressed at high magnetic fields. From the three different transverse modes we find contrasting results both the Γ4(B2g) and Γ5(Eg) symmetry modes C66 and C44 show elastic softening that is enhanced above 30 T, while the characteristic softening of the Γ3(B1g) symmetry mode (C11-C12)/2 is suppressed in high magnetic fields. These results underscore the presence of a hybridization-driven Γ3(B1g) lattice instability in URu2Si2. However, the results from this work cannot be explained by using existing crystalline electric field schemes applied to the quadrupolar susceptibility in a local 5f2 configuration. Instead, we present an analysis based on a band Jahn-Teller effect.
  • Hiraku Saito, Kenta Uenishi, Naoyuki Miura, Chihiro Tabata, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 87 3 033702.1‐033702.5  2018年03月 [査読有り][通常論文]
     
    Magnetization measurements under direct electric current were performed in a toroidal magnetic ordered state of UNi4B to test a recent theoretical prediction of current-induced magnetization in a metallic system lacking local-inversion symmetry. We found that electric current parallel to [2110] and [0001] in the hexagonal 4-index notation induces a uniform magnetization along the [0110] direction. The observed behavior of the induced magnetization is essentially consistent with the theoretical prediction; however, it also shows an inconsistency suggesting that the antiferromagnetic state of UNi4B could not be simply regarded as a uniform toroidal order in the ideal honeycomb layered structure.
  • Satoshi Tsutsui, Yoshio Kobayashi, Jin Nakamura, Michael K. Kubo, Shota Amagasa, Yasuhiro Yamada, Yoshitaka Yoda, Yusei Shimizu, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka, Akira Yamada, Ryuji Higashinaka, Tatsuma D. Matsuda, Yuji Aoki
    HYPERFINE INTERACTIONS 238 2017年11月 [査読有り][通常論文]
     
    Synchrotron-Radiation-based Sm-149 Mossbauer spectroscopy was applied to Sm intermetallics, SmBe13 and SmTi2Al20. Temperature dependence of the Mossbauer parameters in SmBe13 indicate the Sm valence state is purely trivalent. SmBe13 also showed second-order Doppler shift in synchrotron-radiation-based Sm-149 Mossbauer spectroscopy. The Mossbauer parameters obtained in SmTi2Al20 suggest that the Sm valence is fluctuating and the magnitude of the magnetic moment is reduced by hybridization between 4f and conduction electrons and/or effect of crystal electric field.
  • Hiroyuki Hidaka, Seigo Yamazaki, Yusei Shimizu, Naoyuki Miura, Chihiro Tabata, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 86 7 2017年07月 [査読有り][通常論文]
     
    The physical properties of single-crystalline SmBe13 with a NaZn13-type cubic structure have been studied by electrical resistivity (rho), specific heat (C), and magnetization (M) measurements in magnetic fields of up to 9 T. The temperature (T) dependence of rho shows normal metallic behavior without showing the Kondo -ln T behavior, suggesting the weak hybridization effect in this system. Analyses of the temperature dependence of C suggest that the Sm ions of this compound are trivalent and that the crystalline-electric-field (CEF) ground state is a Gamma(8) quartet with a first-excited state of a Gamma(7) doublet located at the energy scale of similar to 90 K. Mean-field calculations based on the suggested CEF level scheme can reasonably well reproduce the T dependence of magnetic susceptibility (chi) below similar to 70 K. These results in the paramagnetic state strongly indicate that the 4 f electrons are well localized with the Sm3+ configuration. At low temperatures, the 4 f electrons undergo a magnetic order at T-M similar to 8.3 K, where chi(T) shows an antiferromagnetic-like cusp anomaly. From the positive Curie-Weiss temperature obtained from the mean-field calculations and from a constructed magnetic phase diagram with multiple regions, we discussed the magnetic structure of SmBe13 below T-M, by comparing with other isostructural MBe13 compounds showing helical-magnetic ordering.
  • Hiroyuki Hidaka, Yusei Shimizu, Seigo Yamazaki, Naoyuki Miura, Ryoma Nagata, Chihiro Tabata, Shota Mombetsu, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 86 2 2017年02月 [査読有り][通常論文]
     
    The thermal and electrical transport properties of single-crystalline LaBe13 have been investigated by specific-heat (C) and electrical-resistivity (rho) measurements. The specific-heat measurements in a wide temperature range revealed the presence of a hump anomaly near 40K in the C(T)= T curve, indicating that LaBe13 has a low-energy Einstein-like-phonon mode with a characteristic temperature of similar to 177 K. In addition, a superconducting transition was observed in the. measurements at the transition temperature of 0.53 K, which is higher than the value of 0.27K reported previously by Bonville et al. Furthermore, an unusual T-3 dependence was found in rho(T) below similar to 50 K, in contrast to the behavior expected from the electron-electron scattering or the electron-Debye phonon scattering.
  • Chihiro Tabata, Milan Klicpera, Bachir Ouladdiaf, Hiraku Saito, Michal Vališka, Klára Uhlířová, Naoyuki Miura, Vladimír Sechovský, Hiroshi Amitsuka
    Physical Review B 96 21 2017年 [査読有り]
     
    The magnetic structure of tetragonal UAu2Si2 was investigated by single-crystal neutron-diffraction experiments. Below T-N= 20 K it orders antiferromagnetically with a propagation vector of k = (2/3,0,0) and magnetic moments of uranium ions pointing along the tetragonal c axis. Weak signs of the presence of a ferromagnetic component of magnetic moment were traced out. Taking into account a group theory calculation and experimental results of magnetization and Si-29 nuclear magnetic resonance, the magnetic structure is determined to be a squared-up antiferromagnetic structure, with a stacking sequence (+ + -) of the ferromagnetic ac-plane sheets along the a axis. This result highlights similar magnetic correlations in UAu2Si2 and isostructural URu2Si2.
  • Chihiro Tabata, Naoyuki Miura, Klara Uhlirova, Michal Valiska, Hiraku Saito, Hiroyuki Hidaka, Tatsuya Yanagisawa, Vladimir Sechovsky, Hiroshi Amitsuka
    PHYSICAL REVIEW B 94 21 2016年12月 [査読有り][通常論文]
     
    Single-crystalline UAu2Si2 has been grown by a floating-zone melting method, and its magnetic, thermal, and transport properties have been investigated through measurements of magnetization, specific heat, and electrical resistivity to reveal its peculiar magnetism. It is shown that UAu2Si2 undergoes a second-order phase transition at T-m = 19 K, which had been believed to be ferromagnetic ordering in the literature, from a paramagnetic phase to an uncompensated antiferromagnetic phase with spontaneous magnetization along the tetragonal c axis (the easy magnetization direction). The magnetic entropy analysis points to the itinerant character of 5f electrons in the magnetic ordered state of UAu2Si2 with large enhancement of the electronic specific heat coefficient of gamma similar to 150 mJ/K(2)mol at 2 K. It also reveals the relatively isotropic crystalline electric field effect of this compound, with contrast to the other relative isostructural compounds. The observed magnetization curves strongly suggest that there is a parasitic ferromagnetic component developing below similar to 50 K in high coercivity with the easy axis along the tetragonal c axis. The results are discussed in the context of evolution of magnetism within the entire family of isostructural UT2Si2 compounds.
  • Satoshi Tsutsui, Ryo Masuda, Yasuhiro Kobayashi, Yoshitaka Yoda, Kota Mizuuchi, Yusei Shimizu, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka, Fumitoshi Iga, Makoto Seto
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 85 8 083704.1‐083704.5  2016年08月 [査読有り][通常論文]
     
    Synchrotron radiation Sm-149 Mossbauer spectroscopy in the energy domain has successfully been carried out on Sm2O3, SmBe13, and SmB6. The isomer shift values were determined in these compounds to discuss their Sm valence state. We also investigated the time window effect on spectra, which is useful for measuring spectra with "high-energy-resolution". This effect makes it possible to discuss the frequency of valence fluctuation in Sm compounds as well as determine Sm valence state precisely using the Sm-149 Mossbauer effect. We discussed the fluctuation of the Sm valence in SmB6.
  • S. Mombetsu, T. Murazumi, H. Hidaka, T. Yanagisawa, H. Amitsuka, P. -C. Ho, M. B. Maple
    PHYSICAL REVIEW B 94 8 2016年08月 [査読有り][通常論文]
     
    We present high-frequency ultrasonic measurements on the filled skutterudite SmOs4Sb12 under hydrostatic pressure. The results clarify that the 4f electrons in this compound transform from delocalized at ambient pressure to localized at high pressures with a crossover pressure of approximately 0.7 GPa. This drastic change in the 4f electrons under pressure is apparently related to the non-Fermi-liquid state, which appears in an intermediate-pressure range of 0.5-1.5 GPa. The results of our analysis strongly suggest that the ferro-octupolar interaction becomes dominant at high pressure. Moreover, we report the pressure dependence of the ultrasonic dispersion, which is due to rattling, over a wide range of ultrasonic frequencies up to 323 MHz. The drastic change in the ultrasonic dispersions and the frequency-dependent elastic anomaly in the C-11 mode at lower temperatures imply a possible coupling between rattling phonons and 4f electrons.
  • Shota Mombetsu, Tatsuya Yanagisawa, Hiroyuki Hidaka, Hiroshi Amitsuka, Shadi Yasin, Sergei Zherlitsyn, Jochen Wosnitza, Pei-Chun Ho, M. Brian Maple
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 85 4 043704.1-043704.4  2016年04月 [査読有り][通常論文]
     
    Our ultrasound results obtained in pulsed magnetic fields show that the filled-skutterudite compound SmOs4Sb12 has the Gamma(67) quartet crystalline-electric-field ground state. This fact suggests that the multipolar degrees of freedom of the Gamma(67) quartet play an important role in the unusual physical properties of this material. On the other hand, the elastic response below approximate to 20 T cannot be explained using the localized 4 f-electron model, which does not take into account the Kondo effect or ferromagnetic ordering. The analysis result suggests the presence of a Kondo-like screened state at low magnetic fields and its suppression at high magnetic fields above 20 T even at low temperatures.
  • 日高宏之
    高圧力の科学と技術 26 1 41 - 47 日本高圧力学会 2016年03月30日 [査読有り][通常論文]
     
    Effects of hydrostatic pressure on a thin film of helimagnet MnSi were reviewed. The MnSi film exhibits similar non-Fermi liquid (NFL) behavior near the pressure-induced quantum critical point to that observed in bulk MnSi, although its temperature range is extended to higher temperature side compared with the bulk sample. Since the NFL behavior of MnSi is related with presence of "Skyrmion", the extended NFL region observed in the thin film may come from stabilization of the Skyrmions due to uniaxial anisotropy. Furthermore, we discussed a general role of hydrostatic pressure in a thin-film sample grown by molecular beam epitaxy.
  • S Mombetsu, T Murazumi, K Hiura, S Yamazaki, Y Shimizu, H Hidaka, T Yanagisawa, H Amitsuka, S Yasin, S Zherlitsyn, J Wosnitza
    Journal of Physics: Conference Series 683 012032 - 012032 2016年02月05日 [査読有り][通常論文]
     
    Ultrasonic measurements were performed on the cage-structure compound SmBe13. We have investigated the magnetic field temperature phase diagram of this material by using pulsed magnetic fields. We found that the low-temperature magnetic order is suppressed by a magnetic field of 43 T for H parallel to [001], which is smaller than the estimated value from mean-field approximation assuming the Gamma(8) quartet crystal-electric-field ground state and simple antiferromagnetic order. We found that the elastic constant C-44 shows softening below the ordering temperature and has a local minimum below 7 T. These facts suggest that the low temperature state is not a simple antiferromagnetically ordered state. In addition, no elastic anomaly due to rattling modes was found in the present measurements.
  • 柳澤 達也, Kanchanavatee N., Janoschek M., Maple M. B., 青木 大, 門別 翔太, 日高 宏之, 網塚 浩, Cong P. T., Yashin S., Zherlitsyn S., Wosnitza J., Huang K.
    日本物理学会講演概要集 71 1960 - 1960 一般社団法人 日本物理学会 2016年
  • 田端 千紘, 三浦 植幸, Uhlířová Klára, Vališka Michal, Sechovský Vladimír, 齋藤 開, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 71 1752 - 1752 一般社団法人 日本物理学会 2016年 

    UAu_2_Si_2_は約19Kで強磁性的な秩序を起こすということを除いて、その低温物性は明らかになっていなかった。最近、我々は本物質の単結晶育成に初めて成功し、詳細な基礎物性測定やNMR測定から19Kの秩序が強磁性ではなく、自発磁化を伴うが本質的には反強磁性であることを明らかにしてきた。本講演では磁気抵抗測定の結果を紹介し、輸送現象の側面から本物質の秩序に伴う磁性の変化について議論する。

  • 三浦 植幸, Uhlířová Klára, Prchal Jiří, 田端 千紘, Sechovský Vladimír, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 71 1755 - 1755 一般社団法人 日本物理学会 2016年 

    UBe_13_はエキゾチックな超伝導を示す重い電子系であり、また、転移温度以上では非フェルミ流体異常を示す。磁性希釈極限系Th_1-x_U_x_Be_13_$(x \leq 0.11)$ では通常フェルミ状態が実現することを我々は既に明らかにしているが、$x = 1$における非フェルミ状態へどのように移行するのかは自明ではない。本公演では全U濃度($0 \leq x \leq 1$)における低温物性(磁化率、電気抵抗、比熱)の実験結果を紹介し、UBe_13_における非フェルミ流体異常の起源について議論する。

  • 田端 千紘, 井原 慶彦, 新村 省悟, 三浦 植幸, 齋藤 開, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 71 1961 - 1961 一般社団法人 日本物理学会 2016年
  • D. Rauch, P. Horenburg, S. Hartwig, F. J. Litterst, S. Suellow, H. Luetkens, C. Baines, S. Yamazaki, H. Hidaka, H. Amitsuka, E. Bauer
    PHYSICAL REVIEW B 92 11 2015年09月 [査読有り][通常論文]
     
    We present a study of the alloying series of the noncentrosymmetric f-electron intermetallic CePt3B1-xSix by means of muon spin rotation and relaxation measurements. In addition, we include a high-pressure magnetization investigation of the stoichiometric parent compound CePt3B. From our data we establish the nature of the magnetic ground state properties of the series, derive the ordered magnetic moment as function of stoichiometry, and gain insight into the evolution of the symmetry of the ordered magnetic state with x. We thus can verify the notion that the behavior of the sample series can essentially be understood within the framework of the Doniach phase diagram. Further, our findings raise the issue of the role the Dzyaloshinskii-Moriya magnetic interaction plays in correlated electron materials and its effect on magnetic fluctuations in such materials.
  • Hiroyuki Hidaka, Shinya Otani, Hiraku Saito, Kaori Tatsumi, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 385 428 - 432 2015年07月 [査読有り][通常論文]
     
    We have performed electrical-resistivity measurements under hydrostatic pressures ranging up to 4.47 GPa on the cubic compound CeAg. A pressure-temperature phase diagram has been revised in a high-pressure range above similar to 2.1 GPa, where the system is known to enter into an unidentified phase through a first-order phase transition. We have found that the electrical resistivity shows a clear kink anomaly below similar to 4 K in this unknown phase. The anomaly shifts to lower temperature with increasing pressure, and shows a tendency to reach absolute zero at similar to 6 GPa, suggesting the presence of a pressure induced quantum critical point around this pressure. We have also observed that a first order phase boundary line, which separates the phase diagram into two regions of a tetragonal phase and the unidentified phase, seems to terminate in a critical end point located at (P-CEP, T-CEP) similar to(3.2 GPa, 200 K). This suggests that the crystal symmetry of the unidentified phase above similar to 2.1 GPa is also tetragonal. (C) 2015 Elsevier B.V. All rights reserved
  • 日高宏之
    未来を拓く高圧力科学技術セミナーシリーズ 40 61 - 67 2015年02月10日 [査読有り][通常論文]
  • 田端 千紘, 井原 慶彦, 網塚 浩, 三浦 植幸, Uhlirova Klara, Valiska Michal, Sechovsky Vladimir, 新村 省悟, 齋藤 開, 日高 宏之, 柳澤 達也
    日本物理学会講演概要集 70 1667 - 1667 一般社団法人 日本物理学会 2015年
  • 稲垣 宏幸, Zherlitsyn S., Wosnitza J., 門別 翔太, 清水 悠晴, 柳澤 達也, 日高 宏之, 網塚 浩, Yazici D., Maple M. B., Cong P. T.
    日本物理学会講演概要集 70 1673 - 1673 一般社団法人 日本物理学会 2015年
  • 柳澤 達也, Wosnitza J., Yazici D., White B. D., Maple M. B., 門別 翔太, 日高 宏之, 網塚 浩, Cong P. T., Zherlitsyn S.
    日本物理学会講演概要集 70 2032 - 2032 一般社団法人 日本物理学会 2015年
  • 田端 千紘, 井原 慶彦, 新村 省悟, 齋藤 開, 三浦 植幸, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 70 2347 - 2347 一般社団法人 日本物理学会 2015年
  • Tatsuya Yanagisawa, Kenta Hiura, Shota Mombetsu, Taro Murazumi, Hiroyuki Hidaka, Hiroshi Amitsuka, Naoyuki Tateiwa, Yoshinori Haga
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS 2014 (SCES2014) 592 1 2015年 [査読有り][通常論文]
     
    The elastic properties of localized 5f-electron system U3Pd20Si6 were studied by means of ultrasonic measurements under magnetic fields. We have measured elastic constants C-11, (C-11-C-12)/2, C-44 and C-L110 = C-B + (C-11-C-12)/6 + C-44 in order to check a possible contribution of electric quadrupoles on the magnetically ordered phases of this compound for Gamma(1) Gamma(3), Gamma(5) and Fi e F3 e F5 symmetries elastic response, respectively. We discovered that an elastic anomaly, which is accompanied by ultrasonic attenuation maximum of F5symmetry mode, at around T* similar to 16 K in zero magnetic field and shifts to lower temperatures with increasing magnetic fields. Since the T* seems to be continuously connected to the lower boundary of a 'spin-flop' region in the magnetic field-temperature phase diagram of U3Pd20Si6, we conclude that a fluctuation of the spin-system of the 8c-site ion exists even just below TN and couples to elastic wave via magneto-elastic coupling with F5-symmetry quadrupoles of U's 5f electron or local charge distributions of the guest U ion.
  • C. Tabata, T. Inami, S. Michimura, M. Yokoyama, H. Hidaka, T. Yanagisawa, H. Amitsuka
    PHILOSOPHICAL MAGAZINE 94 32-33 3691 - 3701 2014年11月 [査読有り][通常論文]
     
    We performed synchrotron X-ray diffraction measurements on a small single crystal of [GRAPHICS] with approximate dimensions of [GRAPHICS] . A backscattering diffraction set-up (2 [GRAPHICS] ) in combination with a Si(660) monochromator ensures a high instrumental resolution of [GRAPHICS] , where [GRAPHICS] denotes a lattice-plane spacing and [GRAPHICS] is its spread expressed as the full width at half maximum (FWHM). We carefully measured the (550) Bragg peak in the temperature range between 5 and 25K, and found it to show no signature of broadening and splitting when "Hidden Order (HO)" sets in below 17.5K. Temperature variation of the peak position closely follows the behaviour of the known linear thermal expansion coefficient. Detailed analysis of the peak width reveals that the tetragonal fourfold rotational symmetry of [GRAPHICS] is conserved in HO within the experimental accuracy of the orthorhombicity of [GRAPHICS] . We also found that the (550) peak profile exhibits a temperature-independent fine structure, which indicates that the tetragonal [GRAPHICS] -axis lattice parameter of the used crystal is distributed with a FWHM of [GRAPHICS] .
  • J. Engelke, D. Menzel, H. Hidaka, T. Seguchi, H. Amitsuka
    PHYSICAL REVIEW B 89 14 144413  2014年04月 [査読有り][通常論文]
     
    In MnSi thin films themagnetic properties of the B20 compound are influenced by induced uniaxial anisotropy. In comparison to bulk MnSi the critical magnetic fields are enhanced and the Skyrmion phase is found to be enlarged within the magnetic phase diagram. Furthermore the ordering temperature depends on the film thickness reaching 43 K for films of around 10 nm and is considerably higher than in bulk crystals (T-c,T-bulk = 29 K). In bulk MnSi the ordering temperature can be reduced by pressure, where at 1.46 GPa the magnetic order is completely suppressed and a non-Fermi-liquid behavior characterized by a T-3/2 law of the resistivity is observed. We present resistance measurements on MnSi thin films under applied pressure of up to 3.44 GPa. Qualitatively, the behavior is similar to bulk MnSi. However, the critical pressure is considerably enhanced to 3.1 GPa, which is assumed to be a consequence of strain. At high pressure non-Fermi-liquid behavior evidenced by a T-3/2 behavior of the resistance is observed up to T-lin = 30 K, i. e., in a larger temperature range than for bulk MnSi. Uniaxial anisotropy might play an important role in this breakdown of Fermi-liquid behavior, since it stabilizes nontrivial spin structures.
  • 田端 千紘, 山崎 聖悟, 伊藤 孝, 髭本 亘, 三浦 植幸, 清水 悠晴, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 69 553 - 553 一般社団法人 日本物理学会 2014年
  • 日浦 健太, 柳澤 達也, 門別 翔太, 村住 太郎, 稲垣 宏幸, 日高 宏之, 網塚 浩, 立岩 尚之, 芳賀 芳範
    日本物理学会講演概要集 69 460 - 460 一般社団法人 日本物理学会 2014年
  • Polarized Light Microscopic Study of the Hidden Order Phase in URu2Si2
    Chihiro Tabata, Masashi Tokunaga, Makoto Yokoyama, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JPS Conf. Proc. 3 011062  2014年 [査読有り][通常論文]
  • Simultaneous Measurements of Elastic Constant and Resistivity near the Tc of Non-BCS-Type Superconductor PrOs4Sb1
    Shota Mombetsu, Taro Murazumi, Kenta Hiura, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka, M. Brian Maple
    JPS Conf. Proc. 3 015021  2014年 [査読有り][通常論文]
  • T. Yanagisawa, S. Mombetsu, H. Hidaka, H. Amitsuka, M. Akatsu, S. Yasin, S. Zherlitsyn, J. Wosnitza, K. Huang, M. Janoschek, M. B. Maple
    Physical Review B - Condensed Matter and Materials Physics 88 19 195150  2013年11月26日 [査読有り][通常論文]
     
    We have measured the elastic constant (C11-C12)/2 in URu2Si2 by means of high-frequency ultrasonic measurements in pulsed magnetic fields H [001] up to 61.8 T in a wide temperature range from 1.5 to 116 K. We found a reduction of (C11-C12)/2 that appears only in the temperature and magnetic field region in which URu 2Si2 exhibits a heavy-electron state and hidden order. This change in (C11-C12)/2 appears to be a response of the 5f electrons to an orthorhombic and volume conservative strain field εxx-εyy with Γ3 symmetry. This lattice instability is likely related to a symmetry-breaking band instability that arises due to the hybridization of the localized f electrons with the conduction electrons and is probably linked to the hidden-order parameter of this compound. © 2013 American Physical Society.
  • 三浦 植幸, 清水 悠晴, 山崎 聖悟, 齋藤 開, 田端 千紘, 門別 翔太, 日高 宏之, 柳澤 達也, 網塚 浩
    日本物理学会講演概要集 68 555 - 555 一般社団法人 日本物理学会 2013年
  • Takahiro Nakada, Makoto Yokoyama, Chihiro Tabata, Hideki Igarashi, Hiroyuki Hidaka, Hiroshi Amitsuka, Kenichi Tenya, Taku J. Sato
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 81 SUPPL.B SB020.1-SB020.4  2012年12月 [査読有り][通常論文]
     
    The nature of competition between incommensurate (IC) and commensurate (C) antiferromagnetic (AF) orders in UPd2Si2 was investigated by performing elastic neutron scattering experiments under uniaxial stress σ. It is found that applying σ along tetragonal [010] direction reduces the IC-AF order, and then stabilizes the C-AF order. The transition temperature from IC- to C-AF phases TNl is enhanced from 109 K (σ = 0) to 112.5 K at (0.8 GPa), while the onset of IC-AF transition TNh is unchanged from 132 K under σ. In addition, c-axis component qz of the IC-AF modulation at 115 K also increases from 0.736 (σ = 0) to 0.747 (0.8 GPa). The magnitude of C-AF moment at 5 K is estimated to be 2.2 μB/U in the entire σ range presently investigated (σ ≤ 0.8 GPa). These features are similar to those obtained from the investigations using hydrostatic pressure p, indicating that applications of p and σ∥ [010] commonly induce the crystal strains which inherently affect a delicate balance of frustrated magnetic interactions between uranium 5f moments. © 2012 The Physical Society of Japan.
  • YANAGISAWA Tatsuya, MOMBETSU Shota, HIDAKA Hiroyuki
    Journal of the Physical Society of Japan 82 1 13601 - 1-5 Physical Society of Japan 2012年11月30日 [査読有り][通常論文]
     
    We have performed ultrasonic measurements on single-crystalline URu2Si2 with pulsed magnetic fields, in order to check for possible lattice instabilities due to the hybridized state and the hidden-order state of this compound. The elastic constant (C11-C12)/2, which is associated with a response to the {\Gamma}3-type symmetry-breaking (orthorhombic) strain field, shows a three-step increase at H > 35 T for H || c at low temperatures, where successive meta-magnetic transitions are observed in the magnetization. We discovered a new fact that the absolute change of the softening of (C11-C12)/2 in the temperature dependence is quantitatively recovered at the suppression of hybridized-electronic state and the hidden order in high-magnetic field for H \perp c associated with the successive transitions. The present results suggest that the {\Gamma}3-type lattice instability, is related to both the emergence of the hybridized electronic state and the hidden-order parameter of URu2Si2. On the other hand, magnetic fields H || [100] and [110] enhance the softening of (C11-C12)/2 in the hidden order phase, while no step-like anomaly is observed up to 68.7 T. We discuss the limitation of the localized-electron picture for describing these features of URu2Si2 by examination of a crystalline electric field model in terms of mean-field theory.
  • H. Hidaka, S. M. Ramos, E. N. Hering, M. B. Fontes, E. B. Saitovitch, S. Otani, T. Wakabayashi, Y. Shimizu, T. Yanagisawa, H. Amitsuka
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011) 391 012019  2012年 [査読有り][通常論文]
     
    We have measured the electrical resistivity of clathrate Ce3Pd20Ge6 under high pressure up to 3.86 GPa in order to investigate pressure effects on two successive phase transitions: O-2(0)-type ferroquadrupole order on Ce-8c site at T-Q = 1.2 K and antiferromagnetic order on Ce-4a site at T-N = 0.75 K. With applying pressure, T-Q stays nearly constant at low pressures and gradually decreases above 2 GPa, while T-N first increases and then decreases above 2.5 GPa. From these results, critical pressures, where T-N T-Q become 0, are roughly estimated to be around 5 - 6 GPa. In addition, we found that the magnetic resistivity, which is obtained by subtracting the resistivity of La3Pd20Ge6 from that Ce3Pd20Ge6, exhibits -lnT dependence in two different temperature ranges, suggesting presence of two different Kondo temperatures originated in the two crystallographic Ce-sites.
  • Yusei Shimizu, Yoshinori Haga, Kenichi Tenya, Tatsuya Yanagisawa, Hiroyuki Hidaka, Hiroshi Amitsuka
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011) 391 1 2012年 [査読有り][通常論文]
     
    We have studied anomalous upper critical field B-c2(T) of a single crystal of UBe13 by DC magnetization measurements down to 0.14 K and up to 8 T. We have observed a broad anomaly and a peak effect below B-c2 in magnetization curves. Although a possibility of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state has been proposed as an origin of the unusual upper critical field by previous works, our results have shown that thermal equilibrium magnetization curves reveal no step-like behavior, which could be observed at 1st-order phase transition from a superconducting mixed state to the FFLO state. We have also investigated anisotropy of B-c2 for B parallel to < 001 > and B parallel to < 110 >, and found that B-c2 for B parallel to < 001 > is larger than B-c2 for B parallel to < 110 > below similar to 0.5 K. These results might indicate that the anomalous upward curvature of B-c2 in UBe13 is related to anisotropy of B-c2 rather than the FFLO state.
  • T. Yanagisawa, H. Saito, Y. Watanabe, Y. Shimizu, H. Hidaka, H. Amitsuka
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011) 391 012079  2012年 [査読有り][通常論文]
     
    Ultrasonic investigations of the elastic constants of non-5f compound ThRu2Si2 were performed in order to highlight possible quadrupolar response in the elastic constants of heavy fermion compound URu2Si2, by using the ThRu2Si2 for backgrounds to subtract the phonon contributions in the elastic constants of URu2Si2. We confirmed that the all-elastic constants of ThRu2Si2 show no elastic anomaly, i.e., increasing monotonically and saturating toward low temperatures, which can be understood regular phonon contributions for the solid states. The background-subtracted (C-11-C-12)2 of URu2Si2 keeps decreasing with decreasing temperatures from 300 K, while other share modes C-44 and C-66 show little change. These contrasts suggest that the Gamma(3)-type quadrupole moment O-2(2) will be still dominant and active in URu2Si2 at low temperatures.
  • 網塚浩, 田端千紘, 日高宏之, 柳澤達也, 横山淳, LUMSDEN M. D., KANCHANAVATEE N., BUTCH N. P., MAPLE M. B.
    NSL News Letter 2012-1 13,51-54  2012年 [査読有り][通常論文]
  • Yusei Shimizu, Yoichi Ikeda, Takumi Wakabayashi, Yoshinori Haga, Kenichi Tenya, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 9 1 - 93701 2011年09月 [査読有り][通常論文]
     
    We have performed low-temperature specific-heat measurements in magnetic fields for a single crystal UBe13. It has been observed that our sample exhibits a superconducting transition at an intermediate temperature (T-c similar to 0.81 K) between previously reported values for two variant samples called H type and L type. The specific heat C(T) of our sample shows a T-3 behavior below similar to 0.7 T-c, which is similar to the behavior of the H-type sample, suggesting the existence of point nodes in the superconducting gap function. We have obtained the upper-critical-field curves H-c2 for the < 001 >, < 111 >, and < 110 > crystal axes, which show no anisotropy at least down to the lowest measured temperature of 0.5 K. We have also derived the Maki parameter kappa(2), and it has been revealed that the kappa(2) steeply decreases isotropically upon cooling just below T-c. Paramagnetic effects and the symmetry of Cooper pairing of UBe13 are discussed.
  • H. Kotegawa, S. Araki, T. Akazawa, A. Hori, Y. Irie, S. Fukushima, H. Hidaka, T. C. Kobayashi, K. Takeda, Y. Ohishi, K. Murata, E. Yamamoto, S. Ikeda, Y. Haga, R. Settai, Y. Onuki
    PHYSICAL REVIEW B 84 5 054524  2011年08月 [査読有り][通常論文]
     
    Strain and resistivity measurements in UIr showed the occurrence of two structural phase transitions under high pressure, indicating the existence of three phases I-III, with slightly different crystal structures. It is suggested that ferromagnetic phases FM1-FM3 emerge in phases I-III, respectively. The pressure-temperature phase diagram was sensitive to the hydrostaticity of pressure. FM3 and superconductivity are observed in the measurements in which Daphne 7373 is used as a pressure-transmitting medium; however they are both absent in the case where petroleum ether is used as a pressure-transmitting medium. These results indicate a close relationship between ferromagnetism and superconductivity.
  • Hiroyuki Hidaka, Sosuke Takahashi, Yusei Shimizu, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 Supplement A 1 - 102 2011年07月 [査読有り][通常論文]
     
    The electrical resistivity rho of the ferromagnet U4Ru7Ge6 has been studied under high pressure up to similar to 4.5 GPa by using an indenter-type high-pressure cell. The Curie temperature T-C = 11.2 K at ambient pressure decreases monotonously with increasing pressure, and seems to disappear at similar to 2.6 GPa, where an enhancement of the coefficient A assuming Fermi liquid regime is observed. This result indicates a presence of a quantum critical point (QCP) of U4Ru7Ge6 at around 2.6 GPa. In addition, non-Fermi liquid behavior (rho similar to T-5/3) predicted by the SCR theory of three dimensional ferromagnet is also observed near the QCP.
  • Tatsuya Yanagisawa, Naoyuki Tateiwa, Taichi Mayama, Hitoshi Saito, Hiroyuki Hidaka, Hiroshi Amitsuka, Yoshinori Haga, Yuichi Nemoto, Terutaka Goto
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 Supplement A 1 - 105 2011年07月 [査読有り][通常論文]
     
    Ultrasonic measurements of U3Pd20Si6 were performed in order to investigate elastic properties of the cage-structured compound U3Pd20Si6 and also examine a presence of ultrasonic dispersion (UD) due to off-center rattling, which has been observed in the elastic constant C-44 of similar systems R3Pd20Ge6 (R = La - Nd). At temperatures over antiferromagnetic ordering at T-N = 19 K, neither an up-turn anomaly nor frequency dependence of the elastic constants, regarding the UD, was found. On the other hand, the elastic constant C-44 shows pronounced softening due to crystalline electric field effect of U4+ ion's Gamma(5) triplet ground state for both 4a and 8c sites. Below T-N, precipitous elastic softening accompanied by a sudden depression of ultrasonic echo was observed in each ultrasonic mode. A drastic change of Delta C-44/C-44 similar to 30% at T-N, in particular, implies a strong magneto-elastic coupling of 5f-electrons or a possible contribution of a ferroquadrupole interaction to the antiferromagnetism in U3Pd20Si6.
  • Yusei Shimizu, Yoichi Ikeda, Takumi Wakabayashi, Kenichi Tenya, Yoshinori Haga, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 Supplement A 1 - 100 2011年07月 [査読有り][通常論文]
     
    Low-temperature specific heat and static dc magnetizetion measurements have been performed for the superconducting state of the heavy-fermion compound UBe13. The superconducting phase diagram B-c2-T (B parallel to [110]) has been obtained by our specific heat and magnetization measurements. From the slope of the upper critical field and specific heat jumps at superconducting transition temperatures in magnetic fields, we have also obtained a temperature dependence of Ginzburg-Landau parameter kappa(2) along [110]. It has been revealed that kappa(2) decreases with decreasing temperature down to 0.5 K, which indicates that a paramagnetic effect may be present at least down to 0.5 K for [110].
  • Tatsuya Yanagisawa, Yoichi Ikeda, Hitoshi Saito, Hiroyuki Hidaka, Hiroshi Amitsuka, Koji Araki, Mitsuhiro Akatsu, Yuichi Nemoto, Terutaka Goto, Pei-Chun Ho, Ryan E. Baumbach, M. Brian Maple
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 4 43601 - 043601-4 2011年04月 [査読有り][通常論文]
     
    Elastic properties of the filled skutterudite compound SmOs4Sb12 have been investigated by ultrasonic measurements. The elastic constant C-11(omega) shows two ultrasonic dispersions at similar to 15 and similar to 53K for frequencies omega between 33 and 316 MHz, which follow a Debye-type formula with Arrhenius-type temperature-dependent relaxation times and remain unchanged even with applied magnetic fields up to 10 T. The corresponding activation energies were estimated to be E-2 = 105K and E-1 = 409 K, respectively. The latter, E-1, is the highest value reported thus far in the Sb-based filled skutterudites. The presence of magnetically robust ultrasonic dispersions in SmOs4Sb12 implies a possibility that an emergence of a magnetically insensitive heavy fermion state in this system is associated with a novel local charge degree of freedom, which causes the ultrasonic dispersion.
  • H. Hidaka, A. Tanaka, S. Takahashi, T. Yanagisawa, H. Amitsuka
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2010) 273 012032  2011年 [査読有り][通常論文]
     
    We have studied the effects of pressure on the incommensurate (IC)-commensurate (C) antiferromagnetic (AFM) phase transition of UPd2Si2 by measuring the electrical resistivity up to 4.21 GPa. We observed that the low-temperature C-AFM (type-I) phase expands and prevails over the IC-AFM phase as pressure is increased. The obtained pressure-temperature phase diagram strongly suggests the existence of a novel bicritical point, more specifically, the so-called Lifshitz point at P-c similar to 3.4 GPa, where magnetic modulation continuously changes from IC to C.
  • Yusei Shimizu, Yoichi Ikeda, Takumi Wakabayashi, Kenichi Tenya, Yoshinori Haga, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hiroshi Amitsuka
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2010) 273 2011年 [査読有り][通常論文]
     
    Static dc magnetization measurements in the superconducting mixed state of a single crystal UBe13 along the [110] axis were performed by means of a capacitance Faraday-force method down to 0.24 K. Below the upper critical field B-c2, not only a peak effect but also an additional broad anomaly have been observed in magnetization curves. We report superconducting phase diagram of UBe13 obtained by our magnetization measurements, including these anomalies.
  • T. Yanagisawa, H. Saitoh, H. Hidaka, H. Amitsuka, T. Cichorek, Z. Henkie, M. B. Maple
    INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2010) 273 012065  2011年 [査読有り][通常論文]
     
    Ultrasonic measurements with frequencies varying between 73 and 160 MHz were performed for the LaRu4As12 single crystal. This As-based filled skutterudite compound is a BCS-type superconductor with T-SC as high as 10.3 K. In order to examine a presence of off-center rattling motion in LaRu4As12, we measured elastic constants C-L111 = (C-11 2C(12) 4C(44))/3 and C-T111 = (C-11- C-12 +4C(44))/3, which are related to longitudinal and transverse sound waves propagating along the [111] direction, respectively. No ultrasonic dispersion was found in the whole temperature range from 1.4 to 300 K.
  • T Yanagisawa, H Saito, T Mayama, Y Ikeda, H Hidaka, M Yokoyama, H Amitsuka
    Journal of Physics: Conference Series 200 1 012236 - 012236 2010年02月 [査読有り]
  • T. Yanagisawa, H. Saito, T. Mayama, Y. Ikeda, H. Hidaka, M. Yokoyama, H. Amitsuka
    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) 200 012236  2010年 [査読有り][通常論文]
     
    Ultrasonic measurements on Rh-substitution system U(Ru1-xRhx)(2)Si-2 (x = 0,0.02 and 0.07) were performed in order to investigate lattice properties for low temperature phase transitions of 'hidden order'(HO) phase and antiferromagnetc (AFM) phase. Elastic constant C-11 vs. T of the x = 0.02 and 0.07 samples exhibit a depression below 80 K, which is similar to a softening in the non-doped sample which had already been reported. The C-11 of x = 0.02 exhibits a step-like anomaly at 14.0 K and an additional softening of 3.2% with minimum at 6.7 K, which correspond to HO and AFM transitions, respectively. The C-11 in x = 0.07 sample only exhibits a shoulder-like anomaly at around 17 K and continue to depress down to 4.2 K.
  • H. Amitsuka, T. Inami, M. Yokoyama, S. Takayama, Y. Ikeda, I. Kawasaki, Y. Homma, H. Hidaka, T. Yanagisawa
    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) 200 012007  2010年 [査読有り][通常論文]
     
    We have studied a puzzling phase below 17.5 K of URu2Si2 by means of resonant Xray scattering (RXS) near the U M-IV absorption edge (E similar to 3.73 keV), using a high-quality single-crystalline sample with low residual stress. We reconfirm that a commensurate (003) superlattice reflection comes purely from antiferromegnetic dipolar order with ordering wave vector Q(AF) = (1, 0, 0). No other traces of significant RXS have been detected in a major region of (h0l) plane, indicating absence of quadrupolar order within a searched Q range including a conceivable nesting vector Q* = (1.4, 0, 0).
  • Yoichi Ikeda, Makoto Yokoyama, Daichi Nishikawa, Hiroyuki Hidaka, Tatsuya Yanagisawa, Kenichi Tenya, Shuzo Kawarazaki, Taku J. Sato, Hideki Yoshizawa, Hiroshi Amitsuka
    INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) 200 SECTION 1 2010年 [査読有り][通常論文]
     
    Elastic neutron-scattering experiment was performed on the heavy-fermion superconductor URu2Si2 under uniaxial stress in order to search a sign of a hidden order parameter. Contour maps of neutron-scattering at 1.5 K were achieved by mesh scanning. No additional magnetic signal exists in (h0l) and (hhl) planes except for a well-known weak antiferromagnetic signal with magnetic-propagation vector of Q = (100) within the present experimental accuracy and scanned area. © 2010 IOP Publishing Ltd.
  • Ikuto Kawasaki, Daichi Nishikawa, Hiroyuki Hidaka, Tatsuya Yanagisawa, Kenichi Tenya, Makoto Yokoyama, Hiroshi Amitsuka
    PHYSICA B-CONDENSED MATTER 404 19 2908 - 2911 2009年10月 [査読有り][通常論文]
     
    In order to investigate magnetic properties around a quantum critical point of CePt1-xRhx alloys, we have performed the ac-susceptibility (chi(ac)) measurements with field frequency ranging from omega/2 pi = 0 (dc magnetization) to 1113 Hz for temperature down to 100mK on polycrystalline CePt1-xRhx (x = 0.5, 0.6). The in-phase component of chi(ac) exhibits a pronounced peak at T-f. The peak magnitude and T-f show significant field-frequency dependence. In addition, a staircaselike hysteresis loop of magnetization was observed below 200mK. From the dynamical analyses of chi(ac) we suggest that CePt0.5Rh0.5 and CePt0.4Rh0.6 can be described as cluster-glass systems. (C) 2009 Published by Elsevier B.V.
  • Hiroyuki Hidaka, Yoichi Ikeda, Ikuto Kawasaki, Tatsuya Yanagisawa, Hiroshi Amitsuka
    PHYSICA B-CONDENSED MATTER 404 19 3005 - 3007 2009年10月 [査読有り][通常論文]
     
    We have carried out specific heat measurements on EuIn2P2 at high magnetic fields perpendicular to the c-axis in the hexagonal crystal structure in order to understand its thermal properties. The temperature dependence of the specific heat exhibits a clear lambda-type anomaly due to a magnetic transition at T-C = 24 K, indicating that the magnetic transition is of second-order. The lambda-type anomaly becomes markedly broader with increasing the magnetic field. This remarkable field-dependence is consistent with the results of previous magnetization measurements which suggest that Eu2+ magnetic moments align ferromagnetically perpendicular to the c-axis below T-C. In addition, a hump in the specific heat is observed around 7 K, which can be ascribed to the Zeeman splitting of the Eu2+ multiplet by internal magnetic fields. (C) 2009 Elsevier B.V. All rights reserved.
  • Tatsuya Yanagisawa, Taichi Mayama, Hiroyuki Hidaka, Hiroshi Amitsuka, Akio Yamaguchi, Koji Araki, Yuichi Nemoto, Terutaka Goto, Naoya Takeda, Pei-Chun Ho, M. Brian Maple
    PHYSICA B-CONDENSED MATTER 404 19 3235 - 3237 2009年10月 [査読有り][通常論文]
     
    Ultrasonic measurements on a Pr0.55Nd0.45Os4Sb12 single crystal for temperature down to 20mK and frequencies up to 245 MHz were performed in order to investigate off-center rattling motion of rare-earth ions. The elastic constant C-11 exhibits double ultrasonic dispersions at similar to 15 and similar to 40 K, which are similar to the features found in NdOs4Sb12. The estimated activation energy E-1 = 240 K corresponding to the 40 K-dispersion, possesses an intermediate value between PrOs4Sb12 (E-1 = 115 K) and NdOs4Sb12 (E-1 = 337 K). (C) 2009 Elsevier B.V. All rights reserved.
  • S. K. Dhar, R. Kulkarni, H. Hidaka, Y. Toda, H. Kotegawa, T. C. Kobayashi, P. Manfrinetti, A. Provino
    JOURNAL OF PHYSICS-CONDENSED MATTER 21 15 156001,1-8  2009年04月 [査読有り][通常論文]
     
    We report magnetization, heat capacity and electrical resistivity measurements on CePtZn, which crystallizes in the orthorhombic TiNiSi type structure. Magnetization and electrical resistivity on the iso-structural series of compounds Ce1-xLaxPtZn (x = 0.1, 0.2 0.5 and 1) were also carried out. The electrical resistivity of CePtZn was also measured in external magnetic fields up to 12 T and under pressures up to 2.66 GPa. We find that CePtZn is a dense Kondo lattice, ordering antiferromagnetically at T-N = 1.7 K, with a comparable Kondo temperature. The magnetic transition temperature, T-N, is continuously suppressed both by the magnetic field and pressure and T-N. 0 around 5-6 T and at 1.2 GPa, respectively. Non-Fermi liquid behavior of resistivity at 4 T and 1.2 GPa and logarithmic divergence of the heat capacity, C-4f/T, at 6 T in a limited temperature region strongly suggest the emergence of a quantum critical point as T-N -> 0.
  • H. Kotegawa, Y. Irie, H. Hidaka, T. C. Kobayashi, D. Kikuchi, H. Sugawara, H. Sato
    PHYSICA B-CONDENSED MATTER 403 5-9 772 - 774 2008年04月 [査読有り][通常論文]
     
    We report that the nuclear spin-spin relaxation rate 1/T-2 shows characteristic peaks in the skutterudite compounds of ROs4Sb12 (R = La, Pr, Nd, and Sm) and PrRu4Sb12. The broadening of Sb-NQR spectrum accompanied with the peak in 1/T-2 suggests that some charge fluctuation exists in these systems and slows down around the peak in 1/T-2. The peaks in 1/T-2 appear around 120 K in all the systems we measured, while the other peaks around 20 K are observed in ROs4Sb12 (R = Pr, Nd, and Sm). The 12 Sb sites are not equivalent at low temperatures in these compounds. (C) 2007 Elsevier B.V. All rights reserved.
  • Hisashi Kotegawa, Keisuke Tabira, Yuta Irie, Hiroyuki Hidaka, Tatuo C. Kobayashi, Daisuke Kikuchi, Kenya Tanaka, Sho Tatsuoka, Hitoshi Sugawara, Hideyuki Sato
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 77 90 - 95 2008年01月 [査読有り][通常論文]
     
    We report resistivity, nuclear quadrupole resonance (NQR), and magnetization measurements under high pressures in a novel heavy fermion compounds SmOs4Sb12. The resistivity and nuclear spin-lattice relaxation rate 1/T-1 show the coherent behavior below a characteristic temperature T* = 20 - 25 K at ambient pressure. Nuclear spin-spin relaxation rate 1/T-2 was found to show a peak of electrical origin around T*. Some charge fluctuation is considered to play an important role in the Kondo effect of SmOs4Sb12. On the other hand, the magnetization at low temperature does not increase under pressures, although the transition temperature increases. The NQR signals are strongly suppressed around the transition temperature and vanishes at low temperatures. These suggest that the ordered state in SmOs4Sb12 is not simple ferromagnetism.
  • H. Kotegawa, H. Hidaka, T. C. Kobayashi, D. Kikuchi, H. Sugawara, H. Sato
    PHYSICAL REVIEW LETTERS 99 15 156408 - 156412 2007年10月 [査読有り][通常論文]
     
    We report Sb-121,Sb- 123 nuclear quadrupole resonance measurements under pressure in a novel heavy fermion (HF) system SmOs4Sb12. The nuclear spin-spin relaxation rate 1/T-2 exhibits a distinct peak near the coherent temperature of the Kondo effect. The isotope effect of Sb-121 and Sb-123 indicates that the peak in 1/T-2 is electrical in origin. The connection between the peak in 1/T-2 and the development of coherency of the Kondo effect is robust even under pressure. It is conjectured that charge fluctuation plays an important role in forming the HF state in SmOs4Sb12.
  • Tatsuo C. Kobayashi, Akihiro Hori, Satoshi Fukushima, Hiroyuki Hidaka, Hisashi Kotegawa, Teruhiko Akazawa, Keiki Takeda, Yasuo Ohishi, Etsuji Yamamoto
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 76 5 1 - 51007 2007年05月 [査読有り][通常論文]
     
    Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of the electrical resistivity, ac-susceptibility and magnetization measurements under high pressure. The phase diagram consists of three magnetic phases FM1-3 and a superconducting phase. The huge enhancement of residual resistivity and the negative magnetoresistance are found in the intermediate pressure region. These behavior may be induced by the pressure-induced structural phase transition and the accompanied phase separation in this pressure range. The superconducting phase with narrow pressure range is embedded in the FM3 phase, adjacent to zero-temperature FM3-to-nonmagnetic transition. The temperature dependence of resistivity above T-SC follows non-Fermi liquid form of T-1.6. From these experimental facts, superconductivity is considered to be associated with the ferromagnetic fluctuation.
  • Hiroyuki Hidaka, Naoki Wada, Hisashi Kotegawa, Tatsuo C. Kobayashi, Daisuke Kikuchi, Hideyuki Sato, Hitoshi Sugawara
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 2 E228 - E230 2007年03月 [査読有り][通常論文]
     
    We have carried out electrical resistivity measurements on PrFe4P12 under high pressure using some kinds of pressure-transmitting mediums in order to investigate the effect of uniaxial stress on a pressure-induced metal-insulator (M-I) transition. In the measurement under uniaxial stress, the M-I transition appears at a lower pressure than in the case of quasi-hydrostatic pressure, indicating that the uniaxial stress is favorable to the insulating phase. On the other hand, the M-I transition appears suddenly with finite M-I transition temperature between 2.55 and 2.66 GPa in the measurement under hydrostatic pressure. This fact suggests that the transition from the antiferroquadrupolar metallic phase to the insulating phase is of first order. (c) 2006 Elsevier B.V. All rights reserved.
  • T. C. Kobayashi, H. Hidaka, T. Fujiwara, M. Tanaka, K. Takeda, T. Akazawa, K. Shimizu, S. Kirita, R. Asai, H. Nakawaki, M. Nakashima, R. Settai, E. Yamamoto, Y. Haga, Y. Onuki
    JOURNAL OF PHYSICS-CONDENSED MATTER 19 12 125205,1-9  2007年03月 [査読有り][通常論文]
     
    We have studied the pressure-temperature phase diagrams in UIr, U3P4, UP2, CeAgSb2 and CeMg2Cu9 by means of the electrical resistivity. Application of pressure suppresses the magnetic ordering shown at ambient pressure in all compounds. In UIr, the pressure-induced superconductivity is observed in the vicinity of the magnetic-nonmagnetic transition. In this article, we review the pressure-temperature phase diagram and the properties of the magnetic nonmagnetic transition in these compounds.
  • T. C. Kobayashi, H. Hidaka, H. Kotegawa, K. Fujiwara, M. I. Eremets
    REVIEW OF SCIENTIFIC INSTRUMENTS 78 2 023909-023909-5  2007年02月 [査読有り][通常論文]
     
    An indenter-type high-pressure cell has been developed for electric and magnetic measurements in low-temperature and high-magnetic-field environments. The maximum pressure achieved at low temperatures is more than 4.5 GPa, which is higher than that of a conventional piston-cylinder cell. The typical sample space at maximum pressure is 1.6 mm in diameter and approximately 0.7 mm in depth, and magnetic measurements such as ac-susceptibility and nuclear magnetic resonance can be performed using a miniature coil. All the components of the indenter cell are made of nonmagnetic materials that have enough thermal conductivity for low-temperature experiments using a He-3/He-4 dilution refrigerator. Another indenter-type cell designed for a commercial superconducting quantum interference device magnetometer is also reported. (c) 2007 American Institute of Physics.
  • Hiroyuki Hidaka, Hisashi Kotegawa, Satoshi Fukushima, Naoki Wada, Tatsuo C. Kobayashi, Hisatomo Harima, Kenji Fujiwara, Daisuke Kikuchi, Hideyuki Sato, Hitoshi Sugawara
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 9 1 - 94709 2006年09月 [査読有り][通常論文]
     
    We have studied the physical properties of a pressure-induced insulating phase in PrFe4P12 via Hall effect, P-31-NMR and magnetization measurements under quasi-hydrostatic pressure. In the Hall effect measurement, a decrease in the number of hole carriers due to the metal-insulator (M-I) transition is confirmed, indicating a band insulating state. The P-31-NMR spectrum exhibits abrupt broadening and the susceptibility is suppressed markedly owing to the M-I transition, suggesting that an antiferromagnetic ordering occurs in the insulating phase and the M-I transition is of first order. Both spectra corresponding to the metallic and insulating phases are observed simultaneously in a wide temperature range near the M-I transition. This fact reflects the sensitivity of the M-I transition to uniaxial stress, which is confirmed in the resistivity measurement under uniaxial stress.
  • Y Watanabe, Y Inada, H Hidaka, H Kotegawa, TC Kobayashi, TD Matsuda, D Aoki
    PHYSICA B-CONDENSED MATTER 378-80 827 - 828 2006年05月 [査読有り][通常論文]
     
    CeAgSb2 crystallizes in the tetragonal ZrCuSi2 type structure (P4/nmm), which consists of Sb-Ce, Sb-Ag-Ce, Sb-Sb layers. It shows the peculiar anisotropic ferromagnetic ordering below 9.7 K with a small ordered moment of 0.33 mu B. Its residual resistivity steeply increases above p(c) congruent to 3.3 GPa where the magnetic order disappears. It is expected that the p-f mixing on the peculiar hollow square pillar-like Fermi surface plays an important role in CeAgSb2, while similar Fermi surfaces were not observed in LaAgSb,. We have measured the anisotropy in the electrical resistivity of CexLa1-xAgSb2 to study the p-f mixing effect. Small humps were observed in the temperature dependence of the resistivity in (CeLa1-xAgSb2)-La-x. We expected them the CDW transition. The CDW state coexisted with the ferromagnetic state around x = 0.2. (c) 2006 Elsevier B.V. All rights reserved.
  • H Kotegawa, T Miyoshi, K Takeda, S Fukushima, H Hidaka, K Tabata, TC Kobayashi, M Nakashima, A Thamizhavel, R Settai, Y Onuki
    PHYSICA B-CONDENSED MATTER 378-80 419 - 420 2006年05月 [査読有り][通常論文]
     
    An antiferromagnet CeNiGe3, which exhibits a quantum critical point at P-C-6-7 GPa, shows the superconductivity in wide pressure range of 1.7-9.3 GPa. In addition to the superconductivity around P-C, the sharp Superconducting transition can be observed by both the resistivity and the susceptibility measurements at lower pressure region far apart from P-C, where 4f-localized Picture seems to be still dominant. Such a superconductivity is a first example in the f-electron systems. (c) 2006 Elsevier B.V. All rights reserved.
  • TC Kobayashi, S Fukushima, H Hidaka, H Kotegawa, T Akazawa, E Yamamoto, Y Haga, R Settai, Y Onuki
    PHYSICA B-CONDENSED MATTER 378-80 355 - 358 2006年05月 [査読有り][通常論文]
     
    High-pressure AC-susceptibility measurement has been carried out in UIr. Three series of peaks corresponding to the successive ferromagnetic transitions indicate the existence of three ferromagnetic phases FM 1-3. The phase boundary between FM2 and FM3 was not realized in the resistivity measurement. The Meissner effect is observed successfully in the pressure range of 2.63-2.74 GPa where the peak of AC-susceptibility survives. This result indicates that the superconducting phase is embedded in the FM3 phase with the ordered moment less than 0.051 mu(B)/U and adjoins the quantum critical point. (c) 2006 Elsevier B.V. All rights reserved.
  • H Kotegawa, K Takeda, T Miyoshi, S Fukushima, H Hidaka, TC Kobayashi, T Akazawa, Y Ohishi, M Nakashima, A Thamizhavel, R Settai, Y Onuki
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 4 "044713 - 1"-"044713-6" 2006年04月 [査読有り][通常論文]
     
    The antiferromagnet CeNiGe3 exhibits superconductivity under pressure. The Neel temperature initially increases with increasing pressure up to 3GPa and then becomes zero at a critical pressure (P-C) that is located at approximately 7GPa. We found that superconductivity emerges from 1.7 GPa in the antiferromagnetic (AF) phase removed from P-C. The superconductivity is realized in a wide pressure region including P-C. The coefficient A in the resistivity and the upper critical field (H,2) significantly change against pressure. A feature of CeNiGe3 is that the moderate heavy fermion state in the AF phase induces superconductivity.
  • Akihiro Hori, Hiroyuki Hidaka, Hisashi Kotegawa, Tatsuo C. Kobayashi, Teruhiko Akazawa, Syugo Ikeda, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Yoshichika Onuki
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 82 - 84 2006年01月 [査読有り][通常論文]
     
    Anisotropic resistivity in UIr has been investigated under high pressure. A huge enhancement of residual resistivity was found under high pressure for the measuring current parallel to the [0 1 0] direction while any anomalies were not observed in the resistivity for [1 0 (1) over bar]. The residual resistivity for [0 1 0] reduced to the original value in the pressure range where superconductivity appears. This anomalous behavior indicates that the ground state in the high-rho(0) state is not simple ferromagnet and the application of pressure induces the first-order transition to slightly different electronic state.
  • H Kotegawa, H Hidaka, Y Shimaoka, T Miki, TC Kobayashi, D Kikuchi, H Sugawara, H Sato
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 8 2173 - 2176 2005年08月 [査読有り][通常論文]
     
    We report nuclear quadrupole resonance (NQR) measurement at ambient pressure and resistivity measurement under high pressure in the new heavy fermion (HF) compound SmOs4Sb12. The NQR spectrum and the nuclear spin-lattice relaxation rate (1/T-1) clearly demonstrate the bulk nature of ferromagnetic ordering below T-C similar to 2 K. The temperature dependence of 1/T-1 exhibits the characteristic behaviors of a Kondo lattice. The application of pressure decreases Kondo temperature and stabilizes the magnetic ordering, which is the same tendency as that found in some Yb-based compounds. The obtained phase diagram indicates SmOs4Sb12 to be in the vicinity of its ferromagnetic critical point.
  • 小林達生, 日高宏之, 福島賢, 小手川恒, 赤沢輝彦, 摂待力生, 大貫惇睦, 山本悦嗣, 芳賀芳範
    固体物理 40 6 415 - 420 2005年06月15日 [査読有り][通常論文]
  • K Takeda, H Hidaka, H Kotegawa, TC Kobayashi, K Shimizu, H Harima, K Fujiwara, K Miyoshi, J Takeuchi, Y Ohishi, T Adachi, M Takata, E Nishibori, M Sakata, T Watanuki, O Shimomura
    PHYSICA B-CONDENSED MATTER 359 1312 - 1314 2005年04月 [査読有り][通常論文]
     
    The powder X-ray diffraction experiments of LiV2O4 have been performed at low temperature and high pressure using synchrotron radiation. In the isothermal experiment at 10 K, the cubic-rhombohedral phase transition corresponding to the metal-insulator transition is found at around 13 GPa. This transition seems to be due to charge ordering of V ions on the analogy of the metal-insulator transition in AlV2O4. (c) 2005 Elsevier B.V. All rights reserved.
  • H Hidaka, Ando, I, H Kotegawa, TC Kobayashi, H Harima, M Kobayashi, H Sugawara, H Sato
    PHYSICA B-CONDENSED MATTER 359 886 - 888 2005年04月 [査読有り][通常論文]
     
    We have studied the electrical resistivity in a skutterudite compound PrFe4P12 under high pressure. An antiferroquadrupolar ordering temperature T-Q decreases monotonously with increasing pressure up to 2.4 GPa. Above 2.4 GPa, the metal-insulator (M-I) transition appears. By applying magnetic field, this M-I transition is suppressed easily and heavy-fermion state is realized. The observed Kondo effect and the field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions of the f electrons of Pr3+ survive even in the insulator phase. (c) 2005 Elsevier B.V. All rights reserved.
  • T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki
    PHYSICA B-CONDENSED MATTER 359 1138 - 1140 2005年04月 [査読有り][通常論文]
     
    Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of electrical resistivity and magnetization. The phase diagram consists of two ferromagnetic phases. The ferromagnetic phase FM1 with T-Cl similar to 46 K at ambient pressure disappears around 1.7 GPa. With further increase of pressure, the phase (FM2) with small ferromagnetic moment appears in the pressure range of P-Cl < P < 2.6 GPa. The superconducting phase exists near the disappearance point of the FM2 phase, indicating that the superconductivity is associated with the ferromagnetic critical fluctuation around P-C2. (c) 2005 Elsevier B.V. All rights reserved.
  • Hiroyuki Hidaka, Ikuma Ando, Hisashi Kotegawa, Tatsuo C. Kobayashi, Hisatomo Harima, Miki Kobayashi, Hitoshi Sugawara, Hideyuki Sato
    Physical Review B - Condensed Matter and Materials Physics 71 7 073102.1-073102.4  2005年02月 [査読有り][通常論文]
     
    We have studied the electrical resistivity of the filled skutterudite compound PrFe 4P 12 under high pressure. The antiferroquadrupolar ordering temperature T Q decreases monotonically with increasing pressure up to 2.4 GPa. Above 2.4 GPa, we have found that a metal-insulator (M-I) transition appears. The insulating state is easily suppressed by a magnetic field. The observed Kondo effect and a field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions survive in the insulating region. The quadrupolar interactions might play an essential role in the M-I transition. PrFe 4P 12 is an unusual compound in that it shows a pressure-induced transition from a metal to an insulator. ©2005 The American Physical Society.
  • H Hidaka, Ando, I, H Kotegawa, TC Kobayashi, H Harima, M Kobayashi, H Sugawara, H Sato
    PHYSICAL REVIEW B 71 7 2005年02月 [査読有り][通常論文]
     
    We have studied the electrical resistivity of the filled skutterudite compound PrFe4P12 under high pressure. The antiferroquadrupolar ordering temperature T-Q decreases monotonically with increasing pressure up to 2.4 GPa. Above 2.4 GPa, we have found that a metal-insulator (M-I) transition appears. The insulating state is easily suppressed by a magnetic field. The observed Kondo effect and a field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions survive in the insulating region. The quadrupolar interactions might play an essential role in the M-I transition. PrFe4P12 is an unusual compound in that it shows a pressure-induced transition from a metal to an insulator.
  • T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 73 11 3129 - 3134 2004年11月 [査読有り][通常論文]
     
    Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of the electrical resistivity and magnetization measurements under high pressure. The phase diagram consists of two magnetic phases, the Ising-like ferromagnetic phase (FM1) at low pressures and another magnetic phase (FM2) with the small ferromagnetic component along the [101] direction at high pressures. Superconductivity is observed in the narrow pressure range near the disappearance point of the FM2 phase, where the temperature dependence of resistivity follows the non-Fermi liquid form of T-1.6. From these experimental facts, the superconductivity is considered to be associated with the critical fluctuation with the disappearance of FM2 phase.
  • T Akazawa, H Hidaka, T Fujiwara, TC Kobayashi, E Yamamoto, Y Haga, R Settai, Y Onuki
    JOURNAL OF PHYSICS-CONDENSED MATTER 16 4 L29 - L32 2004年02月 [査読有り][通常論文]
     
    We report the discovery of pressure-induced superconductivity in ferromagnetic UIr, which lacks inversion symmetry in the crystal structure. The Curie temperature T-CI = 46 K at ambient pressure decreases with increasing pressure, reaching a value of 11 K at 1.5 GPa. It presumably decreases further up to about P-cl = 1.7 GPa. The ferromagnetic region named 'Fl' exists up to P-cl. A second magnetic phase named 'F2' with a low ferromagnetic moment appears in the pressure range frorn 1.9 to 2.4 GPa. In the 'F2' phase, the magnetic transition temperature T-C2 decreases with pressure, from 18 K at 1.9 GPa to approximately zero at P-C2 = 2.6-2.7 GPa. In this critical pressure region, superconductivity appears below T-sc = 0.14 K.

MISC

講演・口頭発表等

担当経験のある科目(授業)

  • 外国語文献交読北海道大学理学部
  • 物理学実験北海道大学理学部
  • 自然科学実験北海道大学

所属学協会

  • 日本物理学会   日本高圧力学会   

共同研究・競争的資金等の研究課題

  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2020年04月 -2023年03月 
    代表者 : 日高 宏之
     
    固体中における多彩な秩序状態は一般に、電荷・磁荷分布の異方性を特徴づける「多極子」で表現することが出来る。特に、結晶構造に空間反転対称性を持たない固体中では、空間反転操作に対して奇関数となる「奇パリティ多極子」が秩序し、通常の金属では発生しえない物理応答、例えば電流によって誘起される結晶格子の歪みなどが観測される可能性がある。本研究では、この奇パリティ多極子秩序の一種である「電気トロイダル四極子秩序」に起因した「電流誘起格子歪み」を観測することを目的とし、局所的に空間反転対称性を持たない金属磁性体における実験的検証を行っている。 2021年度には、昨年度構築した電流格子歪み観測のための「多重環境下熱膨張測定システム」をさらに改良し、そのシステムを用いて実際に電気トロイダル四極子秩序候補物質Cd2Re2O7およびCeCoSiにおける低温・磁場・電流下熱膨張測定を行った。Cd2Re2O7においては、低温秩序状態においてのみ、電気トロイダル四極子秩序に関連すると考えられる電流・磁場誘起格子歪みの発現を初めて発見した。CeCoSiにおいては、電流誘起歪みはこれまでのところ観測されていないが、磁場中各種バルク物性測定とそれらの結果から作成した磁気相図から、本物質の特異な低温秩序状態の解明にとって重要な情報を得た。また、CeCoSiの高圧下熱膨張測定のための準備が完了し、来年度からは高圧下での測定へと着手する予定である。 また上記の研究に加えて、局所的に空間反転対称性を持たない金属磁性体である希土類系RBe13の磁性やウラン系化合物における基本物性と電流誘起磁化の研究など、他の物質系への研究対象の拡張も行っている。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 網塚 浩, 柳澤 達也, 日髙 宏之, 齋藤 開, 鹿内 奈南, 山本 将隆, 中尾 裕則, 田端 千紘, 谷田 博司, 世良 正文, 松村 武, Sechovský Vladimir, Uhlířová Klára, Vališka Michal, Zherlitsyn Sergei, Wosnitza Jochen, Süllow Stefan
     
    本研究の目的は、電子スピンの渦状配置に対応する「トロイダルモーメント」が秩序した金属磁性体に関して予言された新奇な電気磁気効果を実験で検証することにある。現実の強的トロイダル秩序系の候補である層状ウラン化合物UNi4Bの単結晶について電流下での精密磁化測定を行った結果、電流強度に比例して一様磁化が生じることを観測し、理論予想が本質的に正しいことを証明した。一方で電流方向に対する磁化の応答方向が理論予想と単純には合致しない結果も得られ、本系の結晶および磁気構造を精密に再検討する必要があるという新たな課題も提起した。また、同様の電流誘起磁化現象を示す二つの反強磁性体を新たに見出した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2014年04月 -2017年03月 
    代表者 : 柳澤 達也, 網塚 浩, 日髙 宏之
     
    高い対称性を持つ籠状結晶構造に宿る、局所電荷揺らぎや多極子自由度などの複数の量子自由度の結合・拮抗に由来すると考えられる、風変わりな物性に着目し、超音波測定の手法を用いて弾性応答の観点から、カゴ状化合物の量子基底状態を調べた。特に磁場に鈍感な重い電子状態を示すSmOs4Sb12については、パルス磁場を用いた弾性応答により結晶場基底状態を判別し、静水圧力下実験から低温秩序相にΓ67基底状態が有する磁気八極子の相関が強く影響していることを明らかにした。また、カリフォルニア大学との共同研究により作成した新規籠状物質PrNi2Cd20はΓ3非クラマース二重項基底状態を持つことを明らかにした。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2007年 -2009年 
    代表者 : 網塚 浩, 天谷 健一, 日高 宏之, 柳澤 達也, 横山 淳
     
    5f電子系超伝導体URu_2Si_2で長年の謎となっていた弱い反強磁性が結晶中の残留応力により不均一に誘起された磁気秩序相に起因することを微視的に初めて明らかにした。更にこの系の超伝導が隠れた秩序と呼ばれる未知秩序領域内だけで生じ、反強磁性とは共存しないことを示すと共に、隠れた秩序として可能な機構の限定を行った。また関連系の研究から量子相転移点近傍の電子物性及び5f電子の磁性について幾つかの新知見を得た。


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