研究者データベース

網塚 浩(アミツカ ヒロシ)
理学研究院 物理学部門 凝縮系物理学分野
教授

基本情報

所属

  • 理学研究院 物理学部門 凝縮系物理学分野

職名

  • 教授

学位

  • 博士(理学)(北海道大学)

ホームページURL

J-Global ID

研究キーワード

  • 極低温物性実験   

研究分野

  • 自然科学一般 / 磁性、超伝導、強相関系

職歴

  • 2000年 - 2005年 北海道大学助教授(大学院理学研究科物理学専攻) 助教授
  • 2000年 - 2005年 Associate Professor
  • 2005年 - 北海道大学教授(大学院理学研究科物理学専攻) 教授
  • 2005年 - Professor
  • 1995年 - 2000年 北海道大学講師(大学院理学研究科物理学専攻) 講師
  • 1995年 - 2000年 Lecturer
  • 1989年 - 1995年 北海道大学助手(理学部物理学科) 助手
  • 1989年 - 1995年 Research Associate
  • 1995年 同助手(大学院理学研究科物理学専攻) 助手
  • 1995年 Research Associate

学歴

  •         - 1989年   北海道大学   理学研究科   物理学専攻
  •         - 1989年   北海道大学   理学研究科   物理学専攻
  •         - 1989年   北海道大学
  •         - 1989年   北海道大学
  •         - 1987年   北海道大学   理学部
  •         - 1987年   北海道大学

所属学協会

  • 日本中性子科学会   国際ミュオン科学会   日本物理学会   

研究活動情報

その他活動・業績

  • 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) 093701-1-093701-4 2011年09月 [査読無し][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.
  • Yanagisawa, Tatsuya, Ikeda, Yoichi, Saito, Hitoshi, Hidaka, Hiroyuki, Amitsuka, Hiroshi, Araki, Koji, Akatsu, Mitsuhiro, Nemoto, Yuichi, Goto, Terutaka, Ho, Pei-Chun, Baumbach, Ryan E., Maple, M. Brian JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 (4) 043601-1-043601-4 2011年04月 [査読無し][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 012032-1-012032-4 2011年 [査読無し][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.
  • 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 012065-1-012065-4 2011年 [査読無し][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.
  • 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 012084-1-012084-4 2011年 [査読無し][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.
  • Anna Toth, Premala Chandra, Piers Coleman, Gabriel Kotliar, Hiroshi Amitsuka Physical Review B 82 (23) 235116-1-235116-4 2010年12月 [査読無し][通常論文]
     
    The dilute Kondo compound, Th1-xUxRu2Si2, displays non-Fermi-liquid behavior but no zero-point entropy; it thus appears to elude description by known single-ion models. It may also provide a clue to the underlying local degrees of freedom in its dense counterpart, URu2Si2. Here we use high-resolution magnetization studies to cross-check the thermodynamic consistency of previous experiments. Measurement of the field dependence of the temperature scale, T-F(H), associated with Fermi-liquid behavior probes the nature of the underlying impurity fixed point. We find that T-F(H) grows linearly with applied field, in contrast to the quadratic form expected for the two-channel Kondo model. We use a scaling argument to show that the observed behavior of T-F(H) is consistent with the absence of zero-point entropy, suggesting novel impurity behavior in this material. More generally, we suggest the field magnetization as a probe of single-ion physics and make predictions for its behavior in other actinide compounds.
  • T. Kurosawa, N. Momono, H. Amitsuka, M. Oda, M. Ido PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 470 S42 -S43 2010年12月 [査読無し][通常論文]
     
    We investigate the residual gamma-value of the specific heat under the magnetic field H for Ni-substituted La2-xSrxCu1-yNiyO4(x = 0.15, y = 0.015; T-c = 26.5K) and La2-xSrxCuO4(x = 0.15; T-c = 37.0 K) crystals. The reduction of the SC gap estimated by applying the Volovik's relation to Delta gamma vs. H curve is too small to explain the suppression of T-c in Ni-substituted samples, where Delta gamma is the change of gamma under H. We point out the possibility that T-c of Ni-substituted sample decreases through the reduction of the area of the coherent nodal d-wave gap in momentum space, which will play an important role in causing the superconductivity. (C) 2009 Elsevier B.V. All rights reserved.
  • M. Bleckmann, A. Otop, S. Suellow, R. Feyerherm, J. Klenke, A. Loose, R. W. A. Hendrikx, J. A. Mydosh, H. Amitsuka JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 322 (17) 2447 -2453 2010年09月 [査読無し][通常論文]
     
    We present a detaild comparison of the physical properties of as-cast and annealed single crystalline UPt2Si2. We discuss the implications of such phase transitions occuring at comparatively low temperatures for the ground state properties of heavy fermion systems and related correlated electron materils. (C) 2010 Elsevier B.V. All rights reserved.
  • H. Nobukane, K. Inagaki, K. Ichimura, K. Yamaya, S. Takayanagi, I. Kawasaki, K. Tenya, H. Amitsuka, K. Konno, Y. Asano, S. Tanda PHYSICA B-CONDENSED MATTER 405 (11) S277 -S278 2010年06月 [査読無し][通常論文]
     
    We have found parity-violating current-voltage (I-V) curves in a single domain of Sr2RuO4 superconductors The Induced voltage V is an even function of bias current I below superconducting transition temperature The anomalous I-V curves show that positive voltage is detected regardless of the current direction The result implies the parity violation of I-V curves (C) 2009 Elsevier B V All rights reserved
  • M. Yokoyama, Y. Ikeda, I. Kawasaki, D. Nishikawa, K. Tenya, K. Kuwahara, H. Amitsuka INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) 200 012239-1-012239-4 2010年 [査読無し][通常論文]
     
    We investigated effects of magnetic field H on antiferromagnetic (AF) structures in CeRh(1-x)Co(x)In(5) by performing the elastic neutron scattering measurements. By applying H along the [1 (1) over bar0] direction, the incommensurate AF state with the propagation vector of q(h1) = (1/2, 1/2, 0.297) observed at H = 0 is replaced by the commensurate AF state with the q(c2) = (1/2, 1/2, 1/4) modulation above 2 T for x = 0.23, while the AF states with the q(c1) = (1/2, 1/2, 1/2) and q(h2) = (1/2, 1/2, 0.42) modulations seen at H = 0 change into a single q(c1)-AF state above similar to 1.6 T for x = 0.7. These results suggest the different types of AF correlation for Co concentrations of 0.23 and 0.7 in an applied magnetic field H.
  • Hiroyoshi Nobukane, Katsuhiko Inagaki, Satoshi Tsuchiya, Yasuhiro Asano, Koichi Ichimura, Kazuhiko Yamaya, Shigeru Takayanagi, Ikuto Kawasaki, Kenichi Tenya, Hiroshi Amitsuka, Satoshi Tanda JAPANESE JOURNAL OF APPLIED PHYSICS 49 (2) 020209-1-020209-3 2010年 [査読無し][通常論文]
     
    We report our approach to measuring the transport properties in a single chiral order parameter domain of microscale Sr2RuO4 single crystals. Sr2RuO4 single crystals were grown by the solid-phase reaction. Microscale single crystals were deposited from a dispersed liquid, and selected from the result of the chemical composition and crystallinity of the dispersed crystals. The selected crystals attached to gold electrodes show superconducting properties. We also found the anomalous current-voltage characteristics that show that induced voltage is an even function of bias current. (C) 2010 The Japan Society of Applied Physics
  • T. Yanagisawa, H. Saito, T. Mayama, Y. Ikeda, H. Hidaka, M. Yokoyama, H. Amitsuka INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) 200 012236-1-012236-5 2010年 [査読無し][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 012007-1-012007-4 2010年 [査読無し][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 Journal of Physics: Conference Series 200 (SECTION 1) 012065-1-012065-4 2010年 [査読無し][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.
  • 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 [査読無し][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.
  • 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 [査読無し][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 [査読無し][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.
  • M. Yokoyama, I. Kawasaki, S. Oinuma, N. Oyama, K. Tenya, H. Amitsuka PHYSICA B-CONDENSED MATTER 404 (17) 2539 -2542 2009年09月 [査読無し][通常論文]
     
    We performed the elastic neutron scattering experiments on the mixed compounds CeRh1-xCoxIn5, and found that doping Co into CeRhIn5 dramatically changes the antiferromagnetic (AF) structure. The incommensurate AF state with the propagation vector of q(h) = (1/2,1/2,similar to 0.3) observed in pure CeRhIn5 is suppressed with increasing x, and new AF states with an incommensurate q(1) = (1/2,1/2,similar to 0.4) and a commensurate q(c) = (1/2,1/2,1/2) modulations simultaneously develop near the AF quantum critical point: x(c)similar to 0.8. These results suggest that the AF correlations with the q(c) and q(1) modulations enhanced in the intermediate Co concentrations may play a crucial role in the evolution of the superconductivity observed above x similar to 0.4. (C) 2009 Elsevier B.V. All rights reserved.
  • H. Nobukane, K. Inagaki, K. Ichimura, K. Yamaya, S. Takayanagi, I. Kawasaki, K. Tenya, H. Amitsuka, K. Konno, Y. Asano, S. Tanda SOLID STATE COMMUNICATIONS 149 (29-30) 1212 -1215 2009年08月 [査読無し][通常論文]
     
    We observed an unconventional parity-violating vortex in single domain Sr2RuO4 single crystals using a transport measurement. The current-voltage characteristics of submicron Sr2RuO4 show that the induced voltage has anomalous components which are even functions of the bias current. The results may suggest that the vortex itself has a helical internal structure characterized by a Hopf invariant (a topological invariant). We also discuss that the hydrodynamics of such a helical vortex causes the parity violation to retain the topological invariant. (C) 2009 Elsevier Ltd. All rights reserved.
  • Y. H. Matsuda, J. L. Her, T. Inami, K. Ohwada, Z. W. Ouyang, K. Okada, H. Nojiri, A. Mitsuda, H. Wada, K. Yoshimura, H. Amitsuka, N. Kawamura, M. Suzuki, A. Kotani 14TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS14), PROCEEDINGS 190 012019-1-012019-6 2009年 [査読無し][通常論文]
     
    L-edge X-ray magnetic circular dichroism (XMCD) and X-ray absorption spectra (XAS) in several rare-earth elements have been studied in high magnetic fields up to 40 T using a pulsed magnet. XMCD spectrum of Eu in a typical valence fluctuating compound, EuNi2(Si0.18Ge0.82)(2), shows a characteristic two peak structure, reflecting the valence fluctuation. However, in another valence fluctuating compound, YbInCu4, it is found that the XMCD spectrum of Yb shows only a single peak. In contrast to XMCD, two absorption bands in XAS are observed in both EuNi2(Si0.18Ge0.82)(2) and YbInCu4. The intensity ratio between the two absorption bands changes significantly with increasing magnetic field in these materials, suggesting the field-induced valence change. The high magnetic field XMCD and XAS measurements have also been conducted in an antiferromagnetic heavy fermion compound CeRh2Si2. The Ce valence is found to be nearly trivalent and insensitive to magnetic field. The XMCD at Ce L-2-edge increases rapidly around 26 T corresponding to the metamagnetic transition. The XMCD spectra in CeRh2Si2 at high magnetic fields show only a single peak as was reported in a heavy fermion ferromagnetic compound CeRu2Ge2 [1].
  • H. Nobukane, S. Tsuchiya, K. Konno, K. Inagaki, S. Tanda, I. Kawasaki, H. Amitsuka, K. Tenya, Y. Maeno 25TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT25), PART 5 150 052187-1-052187-4 2009年 [査読無し][通常論文]
     
    We observed the power law and the critical exponent of quantum phase transitions by measuring a transient response in an Al/AlOx/Al junction of U(1) superconductors and Sr2RuO4 single crystals of SU(2) superconductors, when magnetic field decreased rapidly from more than the critical field to zero magnetic field below T = 0.1 K. In the Al/AlOx/Al junction, the result shows that the domain length xi is a power function of the quench time tau(Q). The critical exponent is 0.30 +/- 0.01. Moreover, in the Sr2RuO4 crystal, the result shows xi is a power function of tau(Q) and the critical exponent is 0.40 +/- 0.01. From the results of U(1) and SU(2) superconductors, we consider the critical exponents observed by the quenching are derived by a mean-field value in charged systems. Using typical U(1) and SU(2) superconductors, we find that the magnetic quench is efficient method to study formation processes of topological defects for a quantum phase transition near T = 0. http://iopscience.iop.org/article/10.1088/1742-6596/150/5/052187/pdf
  • M. Yokoyama, N. Oyama, H. Amitsuka, S. Oinuma, I. Kawasaki, K. Tenya, M. Matsuura, K. Hirota, T. J. Sato Physical Review 77 (22) 224501-1-224501-5 2008年06月03日 [査読無し][通常論文]
     
    The elastic neutron-scattering experiments were carried out on the solid solutions CeRh1-x Cox In5 to clarify the nature of the antiferromagnetic (AF) state in the vicinity of the quantum critical point: xc ∼0.8. The incommensurate AF order with the wave vector of qh = (1/2,1/2,∼0.3) observed in pure CeRhIn5 is weakly suppressed upon doping with Co, and a commensurate qc = (1/2,1/2,1/2) and an incommensurate q1 = (1/2,1/2,∼0.42) AF structures evolve at intermediate Co concentrations. The AF orders with qc and q1 are enhanced at x=0.7, and furthermore, the qh AF order vanishes. These results suggest that the AF correlations with the qc and q1 modulations are significantly enhanced in the intermediate x range, and may be connected with the evolution of the superconductivity observed above x∼0.3. © 2008 The American Physical Society.
  • Kee Hoon Kim, Yoon Seok Oh, P. A. Sharma, N. Harrison, H. Amitsuka, J. A. Mydosh PHYSICA B-CONDENSED MATTER 403 (5-9) 721 -725 2008年04月 [査読無し][通常論文]
     
    We investigate the Hall coefficient R-H, resistivity, and magnetization of URu2Si2, and U(Ru0.96Rh0.04)(2)Si-2 in the high field regime up to 45 T to trace the electronic structure changes in both high and low temperature regimes. We find that at high temperatures above similar to 7 K, temperature- and field-dependent positions of R-H maxima and magneto resistance maxima coincide with a coherent temperature T-coh at each field. These systematically decrease in temperatures with increasing fields and extrapolate to zero at the field-induced putative quantum critical point (QCP). This observation suggests a collapse of a new energy scale, i.e., a coherent temperature of a heavy quasiparticle band, at the putative field-induced QCP. At lower temperatures, we show there are discontinuous changes of the Hall number n(H) = 1/R(H)e at the phase boundaries. This behavior illustrates that the phase formation is caused by first order reconstructions of the Fermi surface, which we interpret to the polarization of Fermi surface pockets seen in de-Haas van-Alphen (dHvA) measurements. (C) 2007 Elsevier B.V. All rights reserved.
  • M. Yokoyama, N. Oyama, H. Amitsuka, S. Oinuma, I. Kawasaki, K. Tenya, M. Matsuura, K. Hirota PHYSICA B-CONDENSED MATTER 403 (5-9) 812 -814 2008年04月 [査読無し][通常論文]
     
    Polarized neutron scattering experiments were performed on mixed compound CeRh0.6Co0.4In5 to clarify the nature of the low-temperature ordered states. Three nonequivalent Bragg peaks, characterized by the wave vectors of q(h)similar to(1/2,1/2,0.3), q(1)similar to(1/2,1/2,0.4) and q(c) = (1/2, 1/2, 1/2), were observed at 1.4K. These Bragg peaks are found to occur entirely in spin-flip channel. This indicates that these Bragg peaks originate from the magnetic scattering, i.e., the antiferromagnetic orders with three different modulations appear in this compound. (c) 2007 Elsevier B.V. All rights reserved.
  • H. Amitsuka, K. Matsuda, M. Yokoyama, I. Kawasaki, S. Takayama, Y. Ishihara, K. Tenya, N. Tatelwa, T. C. Kobayashi, H. Yoshizawa PHYSICA B-CONDENSED MATTER 403 (5-9) 925 -927 2008年04月 [査読無し][通常論文]
     
    Elastic neutron-scattering and ac-susceptibility measurements have been performed on a 20 single crystal of URu2Si2 under hydrostatic pressure up to similar to 1.1 GPa using Fluorinert 70 & 77 and Daphne oil 7373 as pressure-transmitting media. Daphne oil produces better hydrostaticity of the applied pressure than Fluorinert, resulting in a slight shift of the phase boundary between hidden order and antiferromagnetic order to a lower pressure. The superconducting phase is also influenced, but never overlaps with the antiferromagnetic phase. (c) 2007 Elsevier B.V. All rights reserved.
  • T. Sakakibara, J. Custers, K. Yano, A. Yamada, T. Tayama, Y. Aoki, H. Sato, H. Sugawara, H. Amitsuka, M. Yokoyama PHYSICA B-CONDENSED MATTER 403 (5-9) 990 -993 2008年04月 [査読無し][通常論文]
     
    Measurements of the angle-resolved specific heat C(H, theta) have been performed on PrOs4Sb12 and PrOs4Sb12 in order to examine their superconducting gap structures. In the filled skutterudite PrOs4Sb12, a clear fourfold angular dependence is observed with H rotated in the (10 0) planes, whose field variation suggests gap minima along [10 0] directions. Interestingly, a reversed angular oscillation of C(H, theta) has been observed in the normal state above H-c2 which continues to grow as the high-field antiferroquadrupole phase is approached. In URu2Si2, C(H, theta) with H rotated around the tetragonal c-axis suggests that the nodal structure has rotational symmetry. Comparison between the C(H) data for a- and c-axes indicates the existence of point nodes along the [0 0 1] direction. (c) 2007 Elsevier B.V. All rights reserved.
  • K. Tenya, R. Yamahana, M. Yokoyama, H. Amitsuka, K. Deguchi, Y. Maeno PHYSICA B-CONDENSED MATTER 403 (5-9) 1101 -1103 2008年04月 [査読無し][通常論文]
     
    In order to investigate the chiral-superconducting characteristics as well as the vortex-pinning properties, detailed magnetization measurements of the single crystal Sr2RuO4 have been performed in the field parallel to the [0 0 1] direction. Anomalous pinning features are found at weak fields in the magnetization curves: Tiny flux-jumps successively appear around zero field at temperatures up to at least 0.2 K. At higher temperatures, a small peak of the hysteretic magnetization is observed below 0.1 kOe, which is so-called second magnetization peak (SNIP). The magnitude of the hysteretic magnetization is strongly dependent on (independent of) the field-gradient in the field region below (above) the field where the SNIP appears. Possible origins are discussed from the viewpoints of the pairing symmetry together with the topological change in the vortex-lattice configuration. (C) 2007 Elsevier B.V. All rights reserved.
  • I. Kawasaki, K. Tenya, M. Yokoyama, H. Amitsuka PHYSICA B-CONDENSED MATTER 403 (5-9) 1284 -1286 2008年04月 [査読無し][通常論文]
     
    We have performed specific heat C and magnetic susceptibility chi measurements on the pseudo-binary alloys CePt1-xRhx, synthesized by mixing CePt (a ferromagnetic Kondo-lattice system) and CeRh (an intermediate valence system). As Rh is substituted for Pt, CePt1-xRhx shows a continuous change in the ground state from ferromagnetic order (T-C similar to 6K at x = 0) to a nonmagnetic valence-fluctuation state for x > 0.8. We found a non-Fermi-liquid-like behavior which is characterized by the power law T dependence of C(T) and chi(T), for a wide x range above the ferromagnetic quantum critical point (x(c)similar to 0.8). (C) 2007 Elsevier B.V. All rights reserved.
  • Stefan Suellow, Anna Otop, Anja Loose, Jens Klenke, Oleksandr Prokhnenko, Ralf Feyerherm, Ruud W. A. Hendrikx, John A. Mydosh, Hiroshi Amitsuka JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 77 (2) 024708-1-024708-5 2008年02月 [査読無し][通常論文]
     
    We present a detailed study of the physical properties of single crystalline UPt2Si2. By neutron diffraction we establish the presence of frozen-in strain disorder on the Pt(2)/Si(2) ligand sites within the tetragonal crystal structure. Further, the system undergoes an antiferromagnetic transition at T-N = 32K. In the range T-N < T < T-irr similar or equal to 36 K we observe a cluster glass like phase as result of the disorder. The highly anomalous behavior of the electronic transport properties-metallic along the tetragonal a and localized along the c axis-is a result of the specific type of disorder. Altogether, UPt2Si2 emerges as a model compound to study disorder effects in f electron intermetallics.
  • K. Yano, T. Sakakibara, T. Tayama, M. Yokoyama, H. Amitsuka, Y. Homma, P. Miranovic, M. Ichioka, Y. Tsutsumi, K. Machida PHYSICAL REVIEW LETTERS 100 (1) 017004-1-017004-4 2008年01月 [査読無し][通常論文]
     
    To identify the superconducting gap structure in URu(2)Si(2), we perform field-angle-dependent specific heat measurements for the two principal orientations in addition to field rotations, and a theoretical analysis based on microscopic calculations. The Sommerfeld coefficient gamma(H)'s in the mixed state exhibit a distinctly different field dependence. This comes from point nodes and the substantial Pauli paramagnetic effect of URu(2)Si(2). These two features combined give rise to a consistent picture of superconducting properties, including a possible first order transition of H(c2) at low temperatures.
  • A. V. Silhanek, M. Jaime, N. Harrison, C. D. Batista, H. Amitsuka, S. Nakatsuji, L. Balicas, K. H. Kim, J. A. Mydosh PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 460 682 -683 2007年09月 [査読無し][通常論文]
     
    U(Ru0.96Rh0.04)(2)Si-2 is an anisotropic itinerant 5f heavy electron system which exhibits a single field induced magnetic phase concealing a quantum critical point. We show that the boundary of this phase corresponds to a first order transition as revealed by (1) a large and symmetric specific heat anomaly, (2) an asymmetric magnetocaloric effect on entering and exiting this phase, and (3) a clear history and time-dependent specific heat. We explore the thermodynamic similarities with the mixed valence compound YbInCu4 and show that the out-of-equilibrium properties are analogous to those depicted by the critical state model for hard superconductors. (C) 2007 Elsevier B.V. All rights reserved.
  • K. Matsuda, M. Yokoyama, K. Tenya, H. Amitsuka, H. Yoshizawa JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 (2) 337 -339 2007年03月 [査読無し][通常論文]
     
    We have performed the elastic neutron-scattering and the AC magnetic susceptibility measurements under hydrostatic pressure for URu2Si2 to construct a reliable T-P phase diagram, focusing on the relationship between the hidden order (HO), pressure-induced antiferromagnetism (AF), and non-BCS-type superconductivity (SC). For this purpose, we used the same pressure condition and the same single crystalline sample through all the measurements, because the HO-to-AF phase transition is very sensitive to the experimental conditions such as the quality of sample and applied pressure. The neutron scattering experiment performed under pressures ranging from P = 0.5 to 1.07 GPa showed that the phase transition between HO and AF occurs very sharply at P-M = 0.7GPa for T -> 0. The ordered moment mu(o) of the high-pressure AF phase is estimated to be similar to 0.4 mu(B)/U. (c) 2006 Elsevier B. V. All rights reserved.
  • M. Yokoyama, K. Matsuda, H. Amitsuka, K. Tenya, N. Aso, H. Yoshizawa JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 (2) 328 -330 2007年03月 [査読無し][通常論文]
     
    Inelastic neutron scattering experiments were performed on U(Ru1-x xRh(x))(2)Si-2 with x 0 and 0.02 in order to investigate the variations of the antiferromagnetic ( AF). fluctuations with doping Rh. We have found that the energy of the magnetic excitation observed at Q (1, 0, 0) in the hidden order (HO) phase markedly decreases from similar to 2.6meV (x = 0) to similar to 0 (x = 0.02) with increasing x. In addition, the staggered susceptibility chi Q estimated from the inelastic peak develops in the HO phase at x 0.02, while it is suppressed at x = 0. These results indicate that the AF. fluctuation in the HO phase is signifi. cantly enhanced with doping Rh. (c) 2006 Elsevier B.V. All rights reserved.
  • A. Morishita, K. Matsuda, T. Wakabayashi, I. Kawasaki, K. Tenya, H. Amitsuka JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 (2) 283 -285 2007年03月 [査読無し][通常論文]
     
    We investigated specific heat and magnetic susceptibility for the dilute systems R1-xPrxRu2Si2 (R = Th and Y; x 0: 05 and 0.1). The 4f electronic specific heat C-4f/T shows a Schottky-peak anomaly at similar to 10 K, and the 4f contribution to the magnetic susceptibility chi(4f) shows a saturation tendency below this temperature. These features are common to the R Th and Y systems and scaled by the doped Pr concentration. The experimental results are fairly well described by the singlet-singlet crystalline-electric-field (CEF) level scheme. The Kondo screening seems not to occur in these dilute magnetic systems. (c) 2006 Elsevier B.V. All rights reserved.
  • H. Amitsuka, K. Matsuda, I. Kawasaki, K. Tenya, M. Yokoyama JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 (2) 214 -220 2007年03月 [査読無し][通常論文]
     
    The pressure-temperature phase diagram of the heavy-electron superconductor URu2Si2 has been reinvestigated by AC-susceptibility and elastic neutron-scattering (NS) measurements performed on a small single- crystalline rod (2mm in diameter, 6mm in length) in a Cu-Be clamp-type high- pressure cell (P < 1: 1GPa). At ambient pressure, this sample shows the weakest antiferromagnetic (AF) Bragg reflections reported so far, corresponding to the volume-averaged staggered moment of mu similar to 0.011 mu(B)/U. Under applied pressure, the AF scattering intensity exhibits a sharp increase at P similar to 0.7GPa at low temperatures. The saturation value of the AF scattering intensity above 0.7 GPa corresponds to mu(o) similar to 0.41 mu(B)/U, which is in good agreement with that (similar to 0.39 mu(B)/U) observed above 1.5 GPa in our previous NS measurements. The superconductivity is dramatically suppressed by the evolution of AF phase, indicating that the superconducting state coexists only with the hidden order phase. The presence of parasitic ferro- and/or antiferromagnetic phases with transition temperatures T-1(*) = 120(5), T-2(*) = 36(3) and T-3(*) = 16: 5(5) K and their relationship to the low-T ordered phases are also discussed. (c) 2006 Elsevier B.V. All rights reserved.
  • Yoon Seok Oh, Kee Hoon Kim, N. Harrison, H. Amitsuka, J. A. Mydosh JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 310 (2) 855 -857 2007年03月 [査読無し][通常論文]
     
    Comparative study of U(Ru1-xRhx)(2)Si-2 (x = 0 and 4%) through resistivity, magnetic susceptibility, and Hall coefficient measurements reveals that the coherence temperature, T-coh, of the Rh 4% doped sample clearly decreases by about 10-20% as compared with that of undoped one located around 50 K. Furthermore, T*, a characteristic temperature below which the resistivity shows the T-2 dependence, is also found to decrease by almost the same factor. These findings suggest that the low Rh doping sensitively destroys the itinerant band gap due to the hidden order (HO) through the reduction of the Fermi surface volume in the quasi-particle band. (c) 2006 Elsevier B.V. All rights reserved.
  • Shigeru Takagi, Slut Ishihara, Satoru Saitoh, Hiko-ichiro Sasaki, Hiroshi Tanida, Makoto Yokoyama, Hiroshi Amitsuka Journal of the Physical Sciety of Japan 76 (3) 033708 2007年03月 [査読無し][通常論文]
     
    The still unidentified hidden order (HO) phase below T-0 = 17.5 K in the heavy-electron superconductor URu2Si2 has been investigated by Si-29 NMR on a single crystal under external magnetic field H-ext || c-axis and ambient pressure P. For a previously proposed model of the small-moment antiferromagnetism (SMAF), in which tiny-moment antiferromagnetism (AF) under ambient P is ascribed to spatially homogeneous AF with an ordered moment mu(SMAF) = 0.02-0.04 mu(B), splitting of the line would be expected on the basis of a scaling from the corresponding splitting in the P-induced AF. However, we observed at T = 4.5 K no splitting of the line. This clearly indicates that the SMAF model cannot describe the ambient-P properties. Below To down to similar to 14 K, the 29 Si NMR line shows additional broadening over the paramagnetic width. The additional contribution, however, disappears below similar to 14 K, which indicates that the HO itself produces almost zero internal field at the 29Si site along the c-axis at low temperatures in the HO phase.
  • Y. S. Oh, Kee Hoon Kim, P. A. Sharma, N. Harrison, H. Amitsuka, J. A. Mydosh PHYSICAL REVIEW LETTERS 98 (1) 016401 2007年01月 [査読無し][通常論文]
     
    Temperature- and field-dependent measurements of the Hall effect of pure and 4% Rh-doped URu2Si2 reveal low density (0.03 hole/U) high mobility carriers to be unique to the "hidden order" phase and consistent with an itinerant density-wave order parameter. The Fermi surface undergoes a series of abrupt changes as the magnetic field is increased. When combined with existing de Haas-van Alphen data, the Hall data expose a strong interplay between the stability of the "hidden order," the degree of polarization of the Fermi liquid, and the Fermi surface topology.
  • Makoto Yokoyama, Hiroshi Amitsuka JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 76 136 -139 2007年01月 [査読無し][通常論文]
     
    We have investigated the nature of the competition between hidden order and antiferromagnetic (AF) order in URu2Si2 by performing the neutron scattering experiments under hydrostatic-pressure P, uniaxial-stress sigma, and Rh-substitution conditions. Hidden order observed at ambient pressure in pure URu2Si2 is found to be replaced by the AF order by applying P, s along the tetragonal basal plane, and by doping Rh. We discuss these experimental results on the basis of the crystalline strain calculations, and suggest that this phase transition is generated by the 0.1% increase of the tetragonal c/a ratio. We have also found that the magnetic excitation observed in the hidden order phase vanishes in the AF phase. We show that this variation can be qualitatively explained by assuming the hidden order parameter to be quadrupole.
  • Topological Aspects of Critical Systems and Networks
    World Scientific Publishing Co. Pte. Ltd. 2007年 [査読無し][通常論文]
  • Makoto Yokoyama, Hiroshi Amitsuka, Kei Matsuda, Akifumi Gawase, Narumi Oyama, Ikuto Kawasaki, Kenichi Tenya, Hideki Yoshizawa JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 (10) 023702 2006年10月 [査読無し][通常論文]
     
    We performed elastic neutron scattering experiments on solid solution CeRh1-xCoxIn5 with x = 0.4 to clarify the nature of the antiferromagnetic (AF) phase in the vicinity of the quantum critical point. We observed the incommensurate AF order below T-Nh = 3.5 K. The structure of the incommensurate AF order is basically unchanged from that for pure CeRhIn5. We further found the evolution of a new commensurate AF order with the modulation of q(c) = (1/2, 1/2, 1/2) below T-Nc, = 2.9 K. The volume-averaged moments for the incommensurate and commensurate AF phases are 0.38 mu(B)/Ce and 0.21 mu(B)/Ce, respectively, which are reduced from the incommensurate AF moment (0.75 mu(B)/Ce) for pure CeRhIn5. We suggest from these results that the commensurate magnetic correlation may be tightly coupled with the superconductivity observed below T-c = 1.4 K.
  • P. A. Sharma, N. Harrison, M. Jaime, Y. S. Oh, K. H. Kim, C. D. Batista, H. Amitsuka, J. A. Mydosh Physical Review Letters 97 (15) 156401 2006年10月 [査読無し][通常論文]
     
    A dramatic increase in the total thermal conductivity (kappa) is observed in the hidden order (HO) state of single crystal URu2Si2. Through measurements of the thermal Hall conductivity, we explicitly show that the electronic contribution to kappa is extremely small, so that this large increase in kappa is dominated by phonon conduction. An itinerant BCS or mean-field model describes this behavior well: the increase in kappa is associated with the opening of a large energy gap at the Fermi surface, thereby decreasing electron-phonon scattering. Our analysis implies that the "hidden order" parameter is strongly coupled to the lattice, suggestive of a broken symmetry involving charge degrees of freedom.
  • M Yokoyama, A Gawase, H Amitsuka, K Tenya, H Yoshizawa PHYSICA B-CONDENSED MATTER 378-80 80 -81 2006年05月 [査読無し][通常論文]
     
    We have performed the elastic neutron scattering measurements under the uniaxial stress sigma for the antiferromagnetic (AF) state in CePd2Si2, and found an anisotropy in the sigma dependence of the AF state. The magnitude of the staggered moment is reduced with increasing sigma applied along the tetragonal [110] direction, while it shows nearly independent of sigma for sigma parallel to [001]. Similar behavior is also observed in the sigma dependence of the Neel temperature. From these results, we suggest that both the volume compression and the increase of the c/a ratio lead to the suppression of the AF state. (c) 2006 Elsevier B.V. All rights reserved.
  • AV Silhanek, N Harrison, CD Batista, M Jaime, A Lacerda, H Amitsuka, JA Mydosh Physica B: Condensed Matter 378-80 373 -375 2006年05月 [査読無し][通常論文]
     
    We discuss recent specific heat data in high magnetic fields on URu2Si2 and 4% Rh-doped URu2Si2 as well as previously published de Haas-van Alphen data at lower magnetic fields in pure URu2Si2: both of which are consistent with quasiparticle bands formed from a hybridization between 5f-electron Gamma(5) doublets and regular conduction electrons. The system exhibits itinerant electron metamagnetism that gives rise to a putative quantum critical point at similar to 34-37T (depending on the % of Rh) that is subsequently unstable to field-induced phases. (c) 2006 Elsevier B.V. All rights reserved.
  • Kee Hoon Kim, N. Harrison, H. Amitsuka, M. Jaime, J. A. Mydosh PHYSICA B-CONDENSED MATTER 378-80 31 -35 2006年05月 [査読無し][通常論文]
     
    This paper presents a brief summary of recent electrical transport, magnetization and specific heat measurements on U(Ru1-xRhx)(2)Si-2) (x = 0, 2, 2.5, 3, and 4%) in magnetic fields up to 45 T. The results uncover the formation of multiple phases near their putative metamagnetic quantum critical points at low temperatures. From the established magnetic field versus temperature phase diagram in our series of samples, we find a clear correlation between the field-dependence of the phases and that of the putative quantum critical point. This provides an archetypal example that the field-tuned metamagnetic quantum criticality is intimately related to the formation of thermodynamic phases. (c) 2006 Elsevier B.V. All rights reserved.
  • K Tenya, S Yasuda, M Yokoyama, H Amitsuka, K Deguchi, Y Maeno PHYSICA B-CONDENSED MATTER 378-80 495 -496 2006年05月 [査読無し][通常論文]
     
    Static magnetization measurements of Sr2RuO4 have been performed down to 0.1 K. An anomalous increase of magnetization is observed at H-2 which is located just below H-c2. The onset field H-2 gradually decreases with temperature and seems to merge with H-c2 around I K. Besides the above anomaly, a small kink is found in the magnetization curves at around 9 kOe. These magnetization behaviors are analyzed from the viewpoint of the Ginzburg-Landau theory. (c) 2006 Elsevier B.V. All rights reserved.
  • M Jaime, AV Silhanek, KH Kim, N Harrison, L Balicas, H Amitsuka, JA Mydosh PHYSICA B-CONDENSED MATTER 378-80 82 -83 2006年05月 [査読無し][通常論文]
     
    Specific heat, magnetocaloric effect and magnetization experiments were performed on the 5f-electron system U(Ru0.96Rh0.04)(2)Si-2. This compound exhibits a non-magnetic ground state with a single magnetic field-induced phase between H = 26 and 38 T. We show that the transition into this phase is first-order as revealed by a large irreversible specific heat anomaly and asymmetric magnetocaloric effect. A comparative analysis with the valence transition compound YbInCu4, where similar irreversibility and asymmetry exists, is presented. (c) 2006 Published by Elsevier B.V.
  • YS Oh, KH Kim, N Harrison, PA Sharma, H Amitsuka, JA Mydosh PHYSICA B-CONDENSED MATTER 378-80 989 -990 2006年05月 [査読無し][通常論文]
     
    We investigate the evolution of Hall coefficient R-H in U(Ru0.96Rh0.04)(2)Si-2 across a field-induced phase II, formed to avoid a putative quantum critical point, using a mid-pulse magnet up to 45 T. R-H values at low temperatures increased sharply when the system enters phase II from the neighboring fermi-liquid states stabilized outside phase II. This observation is consistent with a large fermi surface reconstruction to open a partial gap inside phase II. (c) 2006 Elsevier B.V. All rights reserved.
  • K Kuwahara, M Kohgi, K Iwasa, M Nishi, K Nakajima, M Yokoyama, H Amitsuka PHYSICA B-CONDENSED MATTER 378-80 581 -582 2006年05月 [査読無し][通常論文]
     
    We report the field-induced magnetic form factor of the heavy-electron system URu2Si2 obtained by using polarized neutrons. The neutron experiments were performed on the two single crystals at 60 K by applying a magnetic field of 6 T along the tetragonal c-axis. The observed magnetic form factor is close to the theoretical 5f form factor of the free U3+ or U4+ ions calculated by the dipole approximation as other U-based intermetallic superconductors. However, the extrapolated value at sin theta/lambda = 0 (0.07 mu(B)/U) is smaller than the bulk magnetization value (0.10 mu(B)/N). Therefore, this result indicates some contribution other than 5f electrons to the bulk magnetization of URu2Si2. (c) 2006 Elsevier B.V. All rights reserved.
  • AV Silhanek, M Jaime, N Harrison, VR Fanelli, CD Batista, H Amitsuka, S Nakatsuji, L Balicas, KH Kim, Z Fisk, JL Sarrao, L Civale, JA Mydosh PHYSICAL REVIEW LETTERS 96 (13) 026403 2006年04月 [査読無し][通常論文]
     
    We report measurements and analysis of the specific heat and magnetocaloric effect-induced temperature changes at the phase boundary into the single magnetic field-induced phase (phase II) of U(Ru0.96Rh0.04)(2)Si-2, which yield irreversible properties similar to those at the valence transition of Yb1-xYxInCu4. To explain these similarities, we propose a bootstrap mechanism by which lattice parameter changes caused by an electric quadrupolar order parameter within phase II become coupled to the 5f-electron hybridization, giving rise to a valence change at the transition.
  • K Tenya, S Yasuda, M Yokoyama, H Amitsuka, K Deguchi, Y Maeno JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 (2) 103703 2006年02月 [査読無し][通常論文]
     
    We report on detailed measurements of the magnetization of Sr2RuO4 in the superconducting mixed state, performed on a high-quality single crystal in a magnetic field parallel to the [100] axis. A small but distinct kink structure is found at around 9 kOe in the magnetization curve, indicating the presence of an additional superconducting phase transition that has been theoretically predicted to be evidence of the superconductivity with a two-component order parameter. An anomalous increase of magnetization is also observed just below the upper critical field. These anomalies disappear when the field is tilted from the [100] axis by only 3-5 degrees. Possible origins of such magnetization behavior are discussed from the viewpoint of a spin-triplet pairing scenario with a two-component order parameter.
  • K Matsuhira, Y Doi, M Wakeshima, Y Hinatsu, H Amitsuka, Y Shimaya, R Giri, C Sekine, Shirotani, I JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 (3) 1030 -1035 2005年03月 [査読無し][通常論文]
     
    Sm-based filled skutterudite phosphides SmFe4P12, SmRu4P12 and SmOs4P12 synthesized at high temperatures and high pressures have been studied by specific heat measurements in magnetic fields. SmFe4P12 shows an anomaly at 1.6 K attributed to a ferromagnetic transition. SmRu4P12 shows a metal-insulator transition at 16 K. This transition consists of two successive transitions, which suggests orbital and antiferromagnetic orderings. SmOS4P12 shows a sharp anomaly at 4.5 K due to an antiferromagnetic ordering. We discuss the characteristic behavior of those phase transitions and the crystalline electric field state in SmT4P12 (T = Fe, Ru and Os). Interestingly, the magnetic entropy of SmFe4P12 have only 0.16R ln 2 below the ferromagnetic ordering temperature. This suggests a strong spin fluctuation effect. On the other hand, the variation of magnetic entropy in SmRu4P12 and SmOs4P12 reaches to nearly R In 4 below the ordering temperature.
  • Yokoyama, M., Amitsuka, H., Itoh, S., Kawasaki, I., Tenya, K. and Yoshizawa, H.: "Magnetic Excitations in U(Ru1-xRhx)2Si2 (x =< 0.03)", Physica B: Condensed Matter, 359-361: 1129-1131 (2005)*
    2005年 [査読無し][通常論文]
  • Tenya, K., Kawasaki, I., Tameyasu, K., Yasuda, S., Yokoyama, M., Amitsuka, H., Tateiwa, N. and KobayashiT.C.: "Magnetization Study of Heavy Fermion Superconductor URu2Si2 under High Pressures", Physica B: Condensed Matter, 359-361: 1135-1137 (2005)*
    2005年 [査読無し][通常論文]
  • Saitoh, S., Takagi, S., Yokoyama, M. and Amitsuka, H.: "101Ru NQR and Hidden Order in URu2Si2", J. Phys. Soc. Jpn., 74: 2209-2213 (2005)*
    2005年 [査読無し][通常論文]
  • Yokoyama, M., Amitsuka, H., Tenya, K., Watanabe, K., Kawarazaki, S., Yoshizawa, H. and Mydosh, J.A.: "Competition between Hidden Order and Antiferromagnetism in URu2Si2 under Uniaxial Stress Studied by Neutron scattering", Phys. Rev. B, 72: 214419-1-9 ・・・
    2005年 [査読無し][通常論文]
     
    Yokoyama, M., Amitsuka, H., Tenya, K., Watanabe, K., Kawarazaki, S., Yoshizawa, H. and Mydosh, J.A.: "Competition between Hidden Order and Antiferromagnetism in URu2Si2 under Uniaxial Stress Studied by Neutron scattering", Phys. Rev. B, 72: 214419-1-9 (2005)*
  • Kim, K.H., Harrison, N., Amitsuka, H., Jorge, G.A., Jaime, M. and Mydosh J.A.: "Link between Magnetic Field-Induced Quantum Criticality and Phase Formation in U(Ru1-xRhx)2Si2", Physica B: Condensed Matter, 32-34: 359-361 (2005)*
    2005年 [査読無し][通常論文]
  • Amato, A., Graf, M.J., de Visser, A., Amitsuka, H., Andreica, D., and Schenck, A., "Weak-Magnetism Phenomena in Heavy-Fermion Superconductors: Selected MuSR Studies", J. Phys.: Condens. Matter 16: S4403-S4420 (2004).*
    2004年 [査読無し][通常論文]
  • Kim, K.H., Harrison, N., Amitsuka, H., Jorge, G.A., Jaime, M., and Mydosh, J.A., "Nexus between Quantum Criticality and Phase Formation in U(Ru1-xRhx)2Si2", Phys. Rev. Lett. 93: 206402-1-4 (2004).*
    2004年 [査読無し][通常論文]
  • Yokoyama, M., Amitsuka, H., Itoh, S., Kawasaki, I., Tenya, K., and Yoshizawa, H. ''Neutron Scattering Study on Competition between Hidden Order and Antiferromagnetism in U(Ru1-xRhx)2Si2 (x =< 0.05)'', J. Phys. Soc. Jpn. 73: 545-548 (2004).*
    2004年 [査読無し][通常論文]
  • Amitsuka, H. and Yokoyama M., "Inhomogeneous Magnetism and Hidden Order in URu2Si2", Physica B, 329-333:452-455(2003)*
    2003年 [査読無し][通常論文]
  • Kuwahara, K., Sagayama, H., Iwasa, K., Kohgi, M., Miyazaki, S., Nozaki, J., Nogami, A., Yokoyama, M., Amitsuka, H., Nakao H. and Murakami Y.:"High Pressure X-Ray Diffraction Study of URu2Si2", Acta Phys. Pol. B, 34:4307-4310(2003)*
    2003年 [査読無し][通常論文]
  • Amitsuka, H., Tenya, K., Yokoyama, M., Schenck, A., Andreica, D., Gygax, F.N., Amato, A., Miyako, Y., Ying Kai Huang and Mydosh, J.A., "Inhomogeneous Magnetism in URu2Si2 Studied by Muon Spin Relaxation under Hhigh Pressure", Physica B, 326:418-421(2003)
    2003年 [査読無し][通常論文]
  • Matsuda, K., Kohori., Y., Kohara, T., Amitsuka, H., Kuwahara, K. and Matsumoto, T., "The Appearance of Homogeneous Antiferromagnetism in URu2Si2 under High Pressure: A 29Si Nuclear Magnetic Resonance Study", J. Phys.: Condens. Matter, 15:2363-2383(2003).*
    2003年 [査読無し][通常論文]
  • Yokoyama, M., Nozaki, J., Amitsuka, H., Watanabe, K., Kawarazaki, S., Yoshizawa H. and Mydosh J.A., "Nonequilibrium Antiferromagnetic State in the Heavy Electron Compound URu2Si2", Acta Phys. Pol. B, 34:1067-1070(2003)*
    2003年 [査読無し][通常論文]
  • Giri, R., Sekine, C., Shimaya, Y., Shirotani, I., Matsuhira, K., Doi, Y., Hinatsu, Y., Yokoyama M. and Amitsuka, H., "Magnetic Properties of Sm-Based Filled Skutterudite Phosphides", Physica B, 329-333:458-459(2003)*
    2003年 [査読無し][通常論文]
  • Matsuda, K., Kohori, Y., Kohara, T., Amitsuka, H. and Matsumoto, T.:"29^Si NMR Study of URu2Si2 under Pressure", Physica B, 312-313:504-505(2002).*
    2002年 [査読無し][通常論文]
  • Yokoyama, M., Tenya, K. and Amitsuka, H.:"Thorium Dilution Effects of the Heavy Electron Compound URu2Si2", Physica B, 312-313:498-500(2002)*
    2002年 [査読無し][通常論文]
  • Amitsuka, H., Yokoyama, M., Miyazaki, S., Tenya, K., Sakakibara, T., Higemoto, W., Nagamine, K., Matsuda, K., Kohori, Y. and Kohara, T.:"Hidden Order and Weak Antiferromagnetism in URu2Si2", Physica B, 312-313:390-396(2002)*
    2002年 [査読無し][通常論文]
  • Matsuhira, K., Hinatsu, Y., Tenya, K., Amitsuka, H. and Sakakibara T.:"Low-Temperature Magnetic Properties of Pyrochlore Stannates", J. Phys. Soc. Jpn., 71:1576-1582(2002)*
    2002年 [査読無し][通常論文]
  • Sakakibara, T., Tayama, T., Tenya, K., Yokoyama, M., Amitsuka, H., Aoki, D., Onuki, Y., Kletowski, Z. and Kunii, S.:"Multipole ordering in f electron systems", J. Phys. Chem. Solids, 63:1147-1153(2002)*
    2002年 [査読無し][通常論文]
  • Amitsuka, H., Nogami, A., Tenya, K., Yokoyama, M., Miyazaki, S., Sakakibara, T., Nakayama, M., Kimura, N., Aoki, H. and Komatsubara, T.:"Low-Temperature Magnetization Study on the non-Kramers Cubic System Pr3Pd20Ge6", J. Phys. Soc. Jpn., 71 Suppl.:124-・・・
    2002年 [査読無し][通常論文]
     
    Amitsuka, H., Nogami, A., Tenya, K., Yokoyama, M., Miyazaki, S., Sakakibara, T., Nakayama, M., Kimura, N., Aoki, H. and Komatsubara, T.:"Low-Temperature Magnetization Study on the non-Kramers Cubic System Pr3Pd20Ge6", J. Phys. Soc. Jpn., 71 Suppl.:124-126(2002)*
  • Yokoyama, M., Amitsuka, H., Watanabe, K., Kawarazaki, S., Yoshizawa, H. and Mydosh, J.A.:"Effects of Uniaxial Stress on Antiferromagnetic Moment in the Heavy Electron Compound URu2Si2", J. Phys. Soc. Jpn., 71 Suppl.: 264-266(2002)*
    2002年 [査読無し][通常論文]
  • Amitsuka, H., Tenya, K., Yokoyama, M., Schenck, A., Andreica, D., Gygax, F.N., Amato, A., Miyako, Y., Huang Ying Kai and Mydosh, J.A.:"Inhomogeneous Magnetism in URu2Si2 Studied by Muon Spin Relaxation under High Pressure", Physica B, 326:418-421(2002)*
    2002年 [査読無し][通常論文]
  • Sakakibara, T., Tenya, K., Yokoyama, M., Amitsuka, H. and Kunii, S.:"Anomalous Uniaxial Pressure Effect on the Phase IV Ordering in Ce0.75La0.25B6", J. Phys. Soc. Jpn., 71 Suppl.:48-51(2002)*
    2002年 [査読無し][通常論文]
  • Matsuda, K., Kohori, Y., Kohara, T., Kuwahara, K., Amitsuka, H., "Spatially Inhomogeneous Development of Antiferromagnetism in URu_2Si_2: Evidence from ^29Si NMR under Pressure", Phys. Rev. Lett., 87:87203-1-4(2001)*
    2001年 [査読無し][通常論文]
  • Tayama, T., Sakakibara, T., Kitami, K., Yokoyama, M., Tenya, K., Amitsuka, H., Aoki, D., Onuki, Y., Kletowski, Z.:"Antiferro-Quadrupolar Ordering and Multipole Interactions in PrPb_3", J. Phys. Soc. Jpn., 70:248-258(2001)*
    2001年 [査読無し][通常論文]
  • Nagata, T., Fujino, H., Satoh, K., Yamamori, N., Akimitsu, J., Katano, S., Nishi, M., Kakurai, K., Hiroi, M., Sera, M., Kobayashi, N., Tenya, K., Amitsuka, H., Takigawa, T., Inago, H.: "Antiferromagnetic Ordering in the Spin Ladder Compound; Sr_14-xCa_・・・
    2001年 [査読無し][通常論文]
     
    Nagata, T., Fujino, H., Satoh, K., Yamamori, N., Akimitsu, J., Katano, S., Nishi, M., Kakurai, K., Hiroi, M., Sera, M., Kobayashi, N., Tenya, K., Amitsuka, H., Takigawa, T., Inago, H.: "Antiferromagnetic Ordering in the Spin Ladder Compound; Sr_14-xCa_xCu_24O_41", J. Phys. Soc. Jpn., 70: 2419-2424(2001)*
  • Kuwahara, K., Okumura, A., Yokoyama, M., Tenya, K., Amitsuka, H. and Sakakibara, T.: ``Elastic Constants of URu_2Si_2 in Magnetic Fields", Physica B, 281&282: 238-239(2000)*
    2000年 [査読無し][通常論文]
  • Honma, T., Inada, Y., Settai, R., Araki, S., Tokiwa, Y., Takeuchi, T., Sugawara, H., Sato, H., Kuwahara, K., Yokoyama, M., Amitsuka, H., Sakakibara, T., Yamamoto, E., Haga, Y., Nakamura, A., Harima, H., Yamagami, H. and Onuki, Y.: ``Magnetic and Fermi ・・・
    2000年 [査読無し][通常論文]
     
    Honma, T., Inada, Y., Settai, R., Araki, S., Tokiwa, Y., Takeuchi, T., Sugawara, H., Sato, H., Kuwahara, K., Yokoyama, M., Amitsuka, H., Sakakibara, T., Yamamoto, E., Haga, Y., Nakamura, A., Harima, H., Yamagami, H. and Onuki, Y.: ``Magnetic and Fermi Surface Properties of the Ferromagnetic Compound UGa_2", J. Phys. Soc. Jpn., 69: 2647-2659(2000)*
  • Miyako, Y., Yamamoto, Y., Tabata, Y., Marumoto, K., Sato, M., Taniguchi, T., Takeuchi, T., Kawarazaki, S., Amitsuka, H., Ocio, M., Pari P. and Hammann J.: ``Spin Fluctuations and Antiferromagnetic Phase Transitions in Heavy Fermions of Kramers (Ce comp・・・
    2000年 [査読無し][通常論文]
     
    Miyako, Y., Yamamoto, Y., Tabata, Y., Marumoto, K., Sato, M., Taniguchi, T., Takeuchi, T., Kawarazaki, S., Amitsuka, H., Ocio, M., Pari P. and Hammann J.: ``Spin Fluctuations and Antiferromagnetic Phase Transitions in Heavy Fermions of Kramers (Ce compound) and Non-Kramers (U compound) Doublets", J. Phys. Soc. Jpn., 69 suppl. A.: 77-90(2000)*
  • Sakakibara, T., Tayama, T., Kitami, K., Yokoyama, M., Tenya, K., Amitsuka, H., Matsumura, T., Aoki, D., Onuki, Y., Kletowski, Z. and Suzuki T.: ``Interplay of Orbital and Magnetic Degrees of Freedom in f-Electron Systems: The case of PrPb_3 and TmTe", ・・・
    2000年 [査読無し][通常論文]
     
    Sakakibara, T., Tayama, T., Kitami, K., Yokoyama, M., Tenya, K., Amitsuka, H., Matsumura, T., Aoki, D., Onuki, Y., Kletowski, Z. and Suzuki T.: ``Interplay of Orbital and Magnetic Degrees of Freedom in f-Electron Systems: The case of PrPb_3 and TmTe", J. Phys. Soc. Jpn., 69 suppl. A.: 25-32(2000)*
  • Amitsuka, H., Yokoyama, M., Tenya, K., Sakakibara, T., Kuwahara, K., Sato, M., Metoki, N., Honma, T., Onuki, Y., Kawarazaki, S., Miyako, Y. and Mydosh, J.A.: ``Pressure-Induced Magnetic Phase Transition of the 5f Electron System URu_2Si_2", J. Phys. So・・・
    2000年 [査読無し][通常論文]
     
    Amitsuka, H., Yokoyama, M., Tenya, K., Sakakibara, T., Kuwahara, K., Sato, M., Metoki, N., Honma, T., Onuki, Y., Kawarazaki, S., Miyako, Y. and Mydosh, J.A.: ``Pressure-Induced Magnetic Phase Transition of the 5f Electron System URu_2Si_2", J. Phys. Soc. Jpn., 69 suppl. A.: 5-12(2000)*
  • Tenya, K., Kuwahara, K., Amitsuka, H., Sakakibara, T., Ohkuni, H., Inada, Y., Yamamoto, E., Haga, Y. and Onuki, Y.: ``Magnetization Study in the Superconducting Mixed State of URu_2Si_2", Physica B, 281&282: 991-992(2000)*
    2000年 [査読無し][通常論文]
  • Matsuda, K., Kohori, Y., Kohara, T., Kuwahara, K. and Amitsuka H.: ``NMR and NQR Studies of URu_2Si_2", Physica B, 281&282: 989-990(2000)*
    2000年 [査読無し][通常論文]
  • Yokoyama, M., Amitsuka, H., Kuwahara, K., Okumura, A., Tenya, K. and Sakakibara T.: ``Unusual Low Temperature Behavior of the Dilute Uranium Alloys La_{1-x}U_{x}Ru_2Si_2, (x =< 0.07)", Physica B, 281&282: 395-396(2000)*
    2000年 [査読無し][通常論文]
  • Takikawa, T., Sakakibara, T., Matsuhira, K., Tenya, K., Amitsuka H. and Kunii S., ``Magnetic Properties of Ce_{0.75}La_{0.25}B_{6} Under Uniaxial Stress", Physica B, 281&282: 561-562(2000)*
    2000年 [査読無し][通常論文]
  • Sakakibara, T., Honma, S., Tayama, T., Tenya, K., Amitsuka, H., Matsumura, T. and Suzuki T.: ``Low Temperature Magnetization of Antiferro-Quadrupolar Ordering System TmTe", Physica B, 281&282: 566-568(2000)*
    2000年 [査読無し][通常論文]
  • Amitsuka, H., Kuwahara, K., Yokoyama, M., Tenya, K., Sakakibara, T., Mihalik, M. and Menovsky, A.A.: ``Non-Fermi-Liquid Behavior in R_{1-x}U_{x}Ru_2Si_2 ( R=Th, Y and La, x =< 0.07)", Physica B, 281&282: 326-331(2000)*
    2000年 [査読無し][通常論文]
  • Sekine, C., Inaba, T., Shirotani, I., Yokoyama, M., Amitsuka, H. and Sakakibara, T.: ``The specific heat of the filled skutterudite PrRu_4P_12 in magnetic fields", Physica B, 281&282: 303-305(2000)*
    2000年 [査読無し][通常論文]
  • Honma, T., Yamamoto, E., Haga, Y., Settai, R., Araki, S., Inada, Y., Takeuchi, T., Kuwahara, K., Amitsuka, H., Sakakibara, T., Sugawara, H., Sato, H., Nakamura, A. and Onuki, Y.: ``Magnetic, Elastic, Transport and Fermi Surface Properties of a Ferromag・・・
    2000年 [査読無し][通常論文]
     
    Honma, T., Yamamoto, E., Haga, Y., Settai, R., Araki, S., Inada, Y., Takeuchi, T., Kuwahara, K., Amitsuka, H., Sakakibara, T., Sugawara, H., Sato, H., Nakamura, A. and Onuki, Y.: ``Magnetic, Elastic, Transport and Fermi Surface Properties of a Ferromagnetic Compound UGa_2", Physica B, 281&282: 195-196(2000)*
  • Metoki, N., Koike, Y., Haga, Y., Honma, T., Sato, M., Onuki, Y., Kimura, N., Maesawa, K., Amitsuka, H., Yokoyama, M., Kuwahara, K. and Miyako, Y.: ``Neutron-Scattering Studies on Heavy-Fermion Superconductors", Physica B, 280: 362-367(2000)*
    2000年 [査読無し][通常論文]
  • Tayama,T., Honma,S., Tenya,K., Amitsuka,H., Sakakibara,T. and Kunii,S.:"Magnetic Phase Diagram of Ce_xLa_1-xB_6 Studied by Magnetization Measurement", Physica, B259-261:32-33(1999)
    1999年 [査読無し][通常論文]
  • Amitsuka,H., Sato,M., Metoki,N., Yokoyama,M., Kuwahara,K., Sakakibara,T., Morimoto,H., Kawarazaki,S., Miyako,Y. and Mydosh, J.A.:"Effect of Pressure on Tiny Antiferromagnetic Moment in the Heavy-Electron Compound URu_2Si_2", Phys. Rev. Lett., 83:5114-・・・
    1999年 [査読無し][通常論文]
     
    Amitsuka,H., Sato,M., Metoki,N., Yokoyama,M., Kuwahara,K., Sakakibara,T., Morimoto,H., Kawarazaki,S., Miyako,Y. and Mydosh, J.A.:"Effect of Pressure on Tiny Antiferromagnetic Moment in the Heavy-Electron Compound URu_2Si_2", Phys. Rev. Lett., 83:5114-5117(1999)
  • Matsuhira,K., Sakakibara,T., Nomachi,A., Tayama,T., Tenya,K., Amitsuka,H., Maezawa, K. and Onuki, Y.:"Simultaneous Measurement of Magnetization and Magnetostriction in CeRu_2Si_2 at Very Low Temperatures: A Test of the One-Parameter Scaling Property",・・・
    1999年 [査読無し][通常論文]
     
    Matsuhira,K., Sakakibara,T., Nomachi,A., Tayama,T., Tenya,K., Amitsuka,H., Maezawa, K. and Onuki, Y.:"Simultaneous Measurement of Magnetization and Magnetostriction in CeRu_2Si_2 at Very Low Temperatures: A Test of the One-Parameter Scaling Property", J. Phys. Soc. Jpn., 68:3402-3406(1999)
  • Matsuhira,K., Sakakibara,T., Tenya,K. and Amitsuka,H.:"Specific Heat of CeRu_2Si_2 Studied by Constant Volume Dilution", Physica B259-261:73-74(1999)
    1999年 [査読無し][通常論文]
  • Sakakibara,T., Tayama,T., Tenya,K., Amitsuka,H., Aoki,D., Onuki,Y. and Kletowski, Z.:"Magnetization Study of the Antiferro-Quadrupolar Ordering in PrPb_3", Physica B259-261:340-342(1999)
    1999年 [査読無し][通常論文]
  • Amitsuka,H., Kuwahara,K., Okumura,A., Tenya,K., Sakakibara,T., Mihalik,M. and Menovsky, A.A.:"Magnetic Properties of Dilute Uranium Alloys Y_1-xU_xRu_2Si_2(x<0.07)", JJAP Series,11:145-147(1999)
    1999年 [査読無し][通常論文]
  • Sakakibara,T., Tayama,T., Matsuhira,K., Nomachi,A., Honma,S., Tenya,K., Amitsuka,H., Maezawa,K. and Onuki,Y.:"Low Temperature Magnetization and Magnetostriction of CeRu_2Si_2", JJAP Series,11:6-8(1999)*
    1999年 [査読無し][通常論文]
  • Sakakibara,T., Tayama,T., Tenya,K. and Amitsuka,H.:"Magnetization Study of the Phase Diagram of Ce_xLa_1-xB_6",JJAP Series,11:179-181(1999)
    1999年 [査読無し][通常論文]
  • Tenya,K., Yasunami,S., Tayama,T., Amitsuka,H., Sakakibara,T., Hedo,M., Inada,Y., Yamamoto,E., Haga,Y. and Onuki,Y.:"Magnetization Study of the History-Dependent Peak Effect in the Superconducting Mixed State of CeRu_2", J. Phys. Soc. Jpn., 68:224-231(・・・
    1999年 [査読無し][通常論文]
     
    Tenya,K., Yasunami,S., Tayama,T., Amitsuka,H., Sakakibara,T., Hedo,M., Inada,Y., Yamamoto,E., Haga,Y. and Onuki,Y.:"Magnetization Study of the History-Dependent Peak Effect in the Superconducting Mixed State of CeRu_2", J. Phys. Soc. Jpn., 68:224-231(1999)
  • Tenya,K., Yasunami,S., Tayama,T., Amitsuka,H., Sakakibara,T., Hedo,M., Inada,Y., Haga,Y., Yamamoto,E. and Onuki, Y.:"Field-History Dependent Peak Effect in the Superconducting Mixed State of CeRu_2", Physica, B259-261:692-693(1999)
    1999年 [査読無し][通常論文]
  • Hedo,M., Kobayashi,Y., Inada,Y., Yamamoto,E., Haga,Y., Suzuki,J., Metoki,N., Onuki,Y., Sugawara,H., Sato,H., Tenya,K., Tayama,T., Amitsuka,H. and Sakakibara,T.:"Characterization and Flux Flow Experiments in CeRu_2",Physica, B259-261:688-689(1999)
    1999年 [査読無し][通常論文]
  • Amitsuka,H., Kuwahara,K., Yoshida,T., Tenya,K., Sakakibara,T., Mihalik,M. and Menovsky, A.A.:"Anomalous Transport Properties of Dilute Uranium Alloys R_1-xU_xRu_2Si_2 (R=Th, Y; x<0.07)", Physica, B259-261: 412-414(1999)
    1999年 [査読無し][通常論文]
  • Sato,H., Urakawa,J., Aoki,Y., Namiki,T., Sugawara,H., Onuki,Y., Amitsuka,H. and Sakakibara, T. :"Hall Effect and Thermoelectric Power in the Systems Exhibiting the Non-Fermi Liquid Behaviors", Physica B259-261:390-391(1999)
    1999年 [査読無し][通常論文]
  • Amitsuka,H., Honma,T., Sakakibara,T., Mitamura,H., Goto,T., Abe,H., Suzuki,H., Kitazawa,H., Kido,G., Sugiyama, K., Miyako,Y. and Date, M.:"High Field Study of the 5f states in URu_2Si_2 and the Related Compounds", Proceedings of the 4th International S・・・
    1999年 [査読無し][通常論文]
     
    Amitsuka,H., Honma,T., Sakakibara,T., Mitamura,H., Goto,T., Abe,H., Suzuki,H., Kitazawa,H., Kido,G., Sugiyama, K., Miyako,Y. and Date, M.:"High Field Study of the 5f states in URu_2Si_2 and the Related Compounds", Proceedings of the 4th International Symposium on Advanced Physical Fields, edited by Kido,G.:29-32(1999)
  • Tenya,K., Tayama,T., Amitsuka,H., Sakakibara,T., Kimura,N., Yamamoto,E., Haga,Y., Hedo, M., Maezawa,K., Inada,Y., Settai, R. and Onuki,Y.,:"Magnetization Study of Superconductivity in UPt_3 and CeRu_2", JJAP Series,11:53-55(1999)*
    1999年 [査読無し][通常論文]
  • T. Matsumura, S. Nakamura, T. Goto, H. Amitsuka, K. Matsuhira, T. Sakakibara and T. Suzuki: Low Temperature Properties of the Magnetic Semiconductor TmTe, (J. Phys. Soc. Jpn. 67, 612--621, 1998*)
    1998年 [査読無し][通常論文]
  • J.-G. Park, H.-C. Ri, K. Kuwahara and H. Amitsuka: Thermal Hysteresis in Magnetization of Single-Crystal \urs, (J. Magn. \& Magn. Mater. 177-181, 455-456, 1998*)
    1998年 [査読無し][通常論文]
  • M. Hedo, Y. Kobayashi, Y. Inada, E. Yamamoto, Y. Haga, J. Suzuki, N. Metoki, Y. Onuki, H. Sugawara, H. Sato, K. Tenya, T. Tayama, H. Amitsuka and T. Sakakibara: Peak effect in CeRu2: Role of crystalline defects, (J. Phys. Soc. Jpn. 67, 3561-3569, 1998*)
    1998年 [査読無し][通常論文]
  • 1998年 [査読無し][通常論文]
     
    T. Honma, H. Amitsuka, S. Yasunami, K. Tenya, T. Sakakibara, H. Mitamura, T. Goto, G. Kido, S. Kawarazaki, Y. Miyako, K. Sugiyama and M. Date: Incommensurate-Commensurate Magnetic Phase Transitions of the Ising-5f System UPd2Si2: the H-T Phase Diagram and Mean-Field Analysis, (J. Phys. Soc. Jpn. 67, 1017--1028, 1998*)
  • Park, J. -G., McEwen, K. A., de Brion, S., Chouteau, G., Amitsuka, H. and Sakakibara, T. : "High-Field Magnetization Study of Single-Crystal URu2Si2", J. Phys. Condens. Matter, 9 : 3065-3069 (1997)*
    1997年 [査読無し][通常論文]
  • Tayama, T., Sakakibara, T., Tenya, K., Amitsuka, H. and Kunii, S. : "Magnetic phase diagram of CexLa1-xB6 studied by static magnetization measurement at very low temperatures", J. Phys. Soc. Jpn., 66 : 2268-2271 (1997)*
    1997年 [査読無し][通常論文]
  • Sakakibara, T., Tayama, T., Amitsuka, H., Tenya, K., Kunii, S., Suzuki, T. and Ochiai, A. : "Low-temperature magnetization study of the heavy-electron systems", Physica, B230-232 : 307-309 (1997)*
    1997年 [査読無し][通常論文]
  • Matsuhira, K., Sakakibara, T., Amitsuka, H., Tenya, K., Kamishima, K., Goto, T. and Kido, G. : "Single-Site and Inter-Site Effects in Heavy Fermion Compound CeRu2Si2 Studied by Constant Volume Dilution", J. Phys. Soc. Jpn., 66 : 2851-2863 (1997)*
    1997年 [査読無し][通常論文]
  • Mentink, S. A. M., Amitsuka, H., de Visser, A., Slanic, Z., Belanger, D. P., Neumeier, J. J., Thompson, J. D., Menovsky, A. A., Mydosh, J. A. and Mason, T. E. : "Thermodynamic Study of the Magnetic Phase Transition in UNi4B", Physica, B230-232 : 108-11・・・
    1997年 [査読無し][通常論文]
     
    Mentink, S. A. M., Amitsuka, H., de Visser, A., Slanic, Z., Belanger, D. P., Neumeier, J. J., Thompson, J. D., Menovsky, A. A., Mydosh, J. A. and Mason, T. E. : "Thermodynamic Study of the Magnetic Phase Transition in UNi4B", Physica, B230-232 : 108-110 (1997)*
  • Mihalik, M., Kayzel, F. E., Yoshida, T., Kuwahara, K., Amitsuka, H., Sakakibara, T., Menovsky, A. A., Mydosh, J. A. and Franse, J. J. M. : "Superconducting and magnetic properties UNi2Al3 single crystal", Physica, B230-232 : 364-366 (1997)*
    1997年 [査読無し][通常論文]
  • Tenya, K., Ikeda, M., Tayama, T., Kuwahara, K., Amitsuka, H., Sakakibara, T., Yamamoto, E., Maezawa, K., Kimura, N., Settai, R. and Onuki, Y. : "Magnetic properties of heavy fermion superconductors UPt3 and URu2Si2", Physica, B230-232 : 345-347 (1997)*
    1997年 [査読無し][通常論文]
  • Kuwahara, K., Amitsuka, H., Sakakibara, T., Suzuki, O., Nakamura, S., Goto, T., Mihalik, M., Menovsky, A. A., de Visser, A. and Franse, J. J. M. : "Lattice Instability and Elastic Response in the Heavy Electron System URu2Si2", J. Phys. Soc. Jpn., 66 :・・・
    1997年 [査読無し][通常論文]
     
    Kuwahara, K., Amitsuka, H., Sakakibara, T., Suzuki, O., Nakamura, S., Goto, T., Mihalik, M., Menovsky, A. A., de Visser, A. and Franse, J. J. M. : "Lattice Instability and Elastic Response in the Heavy Electron System URu2Si2", J. Phys. Soc. Jpn., 66 : 3251-3258 (1997)*
  • Kuwahara, K., Amitsuka, H., Tenya, K., Sakakibara, T., Suzuki, O., Nakamura, S., Goto, T., Mihalik, M., Menovsky, A. A., de Visser, A. and Franse, J. J. M. : "Search for the quadrupolar instability in URu2Si2", Physica, B230-232 : 77-79 (1997)*
    1997年 [査読無し][通常論文]
  • T. Sakakibara, K. Tenya, M. Ikeda, T. Tayama, H. Amitsuka, E. Yamamoto, K. Maezawa, N. Kimura, R. Settai and Y. Onuki : "Magnetization Study of the Superconducting State of UPt3", J. Phys. Soc. Jpn. Suppl., B65 : 212-218 (1996)*
    1996年 [査読無し][通常論文]
  • T. Tayama, K. Tenya, H. Amitsuka, T. Sakakibara, A. Ochiai and T. Suzuki : "Magnetization study of the valence fluctuation compound Sm3Te4 at very low temperatures", J. Phys. Soc. Jpn., 65 : 3467-3470 (1996)*
    1996年 [査読無し][通常論文]

共同研究・競争的資金等の研究課題

  • 希土類およびアクチノイドを含む強相関電子系の極低温物性

教育活動情報

主要な担当授業

  • 物理学特別講義
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 理学部
  • 磁性物理学
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 磁性、f軌道、結晶場効果、近藤効果、重い電子系、高次多極子
  • 大学院共通授業科目(一般科目):自然科学・応用科学
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 先端機器、技術改革、先端計測、先端分析技術、基礎科学、応用科学
  • 磁性物理学
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 原子軌道、分子軌道、バンド、電子相関、超伝導、熱電材料
  • 物性物理学
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 磁性 スピン 磁気モーメント 交換相互作用 強磁性 反強磁性 スピン波
  • 物理学Ⅱ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 温度、熱エネルギー、熱力学の法則、熱機関、エントロピー、電気、クーロンの法則、電場、磁場、ビオ・サバールの法則、電磁誘導、電気回路、インピーダンス、電力、電磁波

大学運営

学内役職歴

  • 2014年4月1日 - 2015年3月31日 総長補佐
  • 2014年4月1日 - 2017年3月31日 研究戦略室室員
  • 2014年4月1日 - 2017年3月31日 創成研究機構副機構長
  • 2015年4月1日 - 2017年3月31日 総長補佐
  • 2017年4月1日 - 2019年3月31日 教育研究評議会評議員
  • 2017年4月1日 - 2019年3月31日 大学院理学院長
  • 2019年4月1日 - 2021年3月31日 教育研究評議会評議員
  • 2019年4月1日 - 2021年3月31日 大学院理学院長

委員歴

  • 2009年   日本物理学会   北海道支部委員長   日本物理学会
  • 2008年   日本物理学会   代議員   日本物理学会


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