基本情報

所属

• 理学研究院　物理学部門　電子物性物理学分野

職名

• 助教

学位

• 博士(理学)（大阪大学）

科研費研究者番号

• 80746561

J-Global ID

• 201601017890293429

研究キーワード

• 磁気共鳴   熱測定   強相関電子系   電子物性   分子性導体   

研究分野

• 自然科学一般 / 磁性、超伝導、強相関系

担当教育組織

•  学士課程　理学部
•  修士課程　理学院

職歴

• 2015年12月 - 現在 北海道大学 大学院理学研究院 物理学部門 助教
• 2014年04月 - 2015年12月 東京大学 物性研究所 特任研究員

学歴

•         - 2014年03月   大阪大学   大学院理学研究科   博士後期課程
•         - 2011年03月   大阪大学   大学院理学研究科   博士前期課程
•         - 2009年03月   大阪大学   理学部   化学科

所属学協会

• 分子科学会   日本物理学会   日本熱測定学会   

研究活動情報

論文

• Magnetic field induced insulator-to-metal Mott transition in λ-type organic conductors

  S. Fukuoka, T. Oka, Y. Ihara, A. Kawamoto, S. Imajo, K. Kindo

  Physical Review B 109 19 2024年05月13日
• Antiferromagnetic ordering and estimation of the exchange interaction in the π-d system λ-(BEDSe-TTF)2FeCl4 studied using 13CNMR

  Rikumaru Saito, Takuya Kobayashi, Hiromi Taniguchi, Shuhei Fukuoka, Atsushi Kawamoto

  Physical Review B 108 15 2023年10月09日
• Survival of magnetic correlations above the ordering temperature in the ferromagnetically ordered classical kagome magnet Li 9 Cr 3 ( P 2 O 7 ) 3 ( PO 4 ) 2

  R. Kumar, A. Chakraborty, S. Fukuoka, F. Damay, E. Kermarrec, P. L. Paulose, Y. Ihara

  Physical Review B 107 13 2023年04月24日
• 13C NMR study of the stabilization of the antiferromagnetic ground state and the emergence of unconventional magnetic state in a molecular π−d system

  S. Fukuoka, Y. Ito, Y. Ihara, A. Kawamoto

  Physical Review B 105 13 2022年04月25日 [査読有り]
  
• Magnetic state in the quasi-two-dimensional organic conductor λ−(BEST)2FeCl4 and the path of π−d interaction

  Rikumaru Saito, Youhei Iida, Takuya Kobayashi, Hiromi Taniguchi, Noriaki Matsunaga, Shuhei Fukuoka, Atsushi Kawamoto

  Physical Review B 105 16 2022年04月11日 [査読有り]
  
• Antiferromagnetic Ground State of Molecular π-d System λ-(BEDT-STF)2FeCl4 Studied by Site-Selective Magnetization and Thermodynamic Measurements

  Shuhei Fukuoka, Atsushi Kawamoto

  Chemistry Letters 51 4 375 - 385 2022年02月01日 [査読有り]
   

  Organic conductors consisting of donor and anion molecules provide various important study fields such as superconductivity and electron correlation. pi electrons are responsible for the emergence of these phenomena. On the other hand, the coexistent systems of pi electrons and localized 3d spins have been realized by introducing magnetic anions. Such coexistent systems are called pi-d systems. In pi-d systems, various fascinating magnetic and conducting phenomena are observed due to the coupling of pi electrons and localized 3d electrons (pi-cl interaction). One of the most striking phenomena is magnetic field-induced superconductivity, which is first observed in X-(BETS)(2) FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. On the other hand, X-(BETS)(2)FeCl4 shows a metal-insulator transition accompanying an antifeffomagnetic ordering at TN of 8.3 K and the unconventional antifeffomagnetic state that 3d spins behave as if they stay paramagnetic even below TN. These phenomena are also considered to be caused by the pi-cl interaction, but their mechanisms have not been demonstrated.Recently, a new lambda-type pi-cl system of lambda-(BEDT-STF)(2)FeCl4, where BEDT-STF is bis(ethylenedithio)dithiadiselenafulvalene, has been developed. In this review, the influence of bandwidth control by donor substitution and the dilution effect of magnetic ions on the magnetic properties of the pi-d system will be discussed. We will demonstrate that site-selective magnetization measurements by C-13 NMR and Fe-57 Mossbauer measurements and heat capacity measurements provide important information to understand the mechanism of unconventional magnetic properties in pi-d systems. We would also like to introduce the advantages of the C-13 NMR measurements using one-sided C-1(3)-enriched donor molecules, which are the key technique in our experiments.
• Magnetic properties of the Shastry-Sutherland lattice material BaNd2ZnO5

  Yuto Ishii, G. Sala, M. B. Stone, V. O. Garlea, S. Calder, Jie Chen, Hiroyuki K. Yoshida, Shuhei Fukuoka, Jiaqiang Yan, Clarina dela Cruz, Mao-Hua Du, David S. Parker, Hao Zhang, Cristian D. Batista, Kazunari Yamaura, A. D. Christianson

  Physical Review Materials 5 6 2021年06月28日 [査読有り]
  
• Effects of Anion Substitution on Unconventional Antiferromagnetic Ground State of Molecular π–d System λ-(BEDT-STF)2FexGa1−xCl4

  Shuhei Fukuoka, Kaduki Haruyama, Yoshihiko Ihara, Atsushi Kawamoto

  Journal of the Physical Society of Japan 90 4 043702 - 043702 2021年04月15日 [査読有り]
   

  lambda-type molecular pi-d systems are coupled systems consisting of pi electron systems with strong magnetic interactions and 3d electron systems with weak magnetic interactions. They exhibit an unconventional antiferromagnetic ground state in which the 3d spins behave as if they remain paramagnetic even below T-N. In this study, we investigated the anion substitution effects of lambda-(BEDT-STF)(2)FexGa1-xCl4 by heat capacity measurements. A Schottky-type anomaly was observed for all alloy compounds (0.1 <= x <= 1.0). We found that the exchange field, which is the origin of this Schottky-type anomaly, decreases with the Fe content. Based on these results, we discuss the role of each magnetic interaction involved in the stabilization of the antiferromagnetic ground state and emergence of paramagnetic-like behavior.
• Thermodynamic Investigation on Antiferromagnetic Ordered State of the Molecular π–d System λ-(BEDT-STF)2FeCl4

  Shuhei Fukuoka, Takaaki Minamidate, Noriaki Matsunaga, Yoshihiko Ihara, Atsushi Kawamoto

  Journal of the Physical Society of Japan 89 7 073704 - 073704 2020年07月15日 [査読有り][通常論文]
   

  We performed heat capacity measurements on the molecular pi-d system lambda-(BEDT-STF)(2)FeCl4 to discuss the unconventional paramagnetic-like behavior. We observed a Schottky-type anomaly below T-N of 16 K which is inherent in the 3d spin degrees of freedom as is observed in lambda-(BETS)(2)FeCl4. This result suggests that the paramagnetic-like behavior is not a unique behavior in lambda-(BETS)(2)FeCl4 but a universal behavior in lambda-type pi-d systems. In the case of lambda-(BETS)(2)FeCl4, a metal-insulator (M-1) transition occurs simultaneously with the antiferromagnetic transition at T-N of 8.3 K, and the paramagnetic-like behavior is observed below T-N. Because lambda-(BEDT-STF)(2)FeCl4 is insulating over the entire temperature range, our results revealed that the M-I transition is not essential for the emergence of the paramagnetic-like behavior. By comparing the thermodynamic nature of lambda-(BEDT-STF)(2)FeCl4 and lambda-(BETS)(2)FeCl4, we discuss the possible origin of the paramagnetic-like behavior.
• Selective observation of sublattice magnetization in the molecular π−d system λ−(BEDT−STF)2FeCl4 studied by C13 NMR

  S. Fukuoka, T. Minamidate, Y. Ihara, A. Kawamoto

  Physical Review B 101 18 2020年05月01日 [査読有り][通常論文]
  
• Microscopic coexistence of superconductivity and charge order in the organic superconductor beta"-(BEDT-TTF)(4)[(H3O)Ga(C2O4)(3)]center dot C6H5NO2

  Ihara Y, Moribe K, Fukuoka S, Kawamoto A

  PHYSICAL REVIEW B 100 6 2019年08月20日 [査読有り][通常論文]
  
• Magnetic and Electronic Properties of pi-d Interacting Molecular Magnetic Superconductor kappa-(BETS)(2)FeX4 (X = Cl, Br) Studied by Angle-Resolved Heat Capacity Measurements

  Fukuoka Shuhei, Fukuchi Sotarou, Akutsu Hiroki, Kawamoto Atsushi, Nakazawa Yasuhiro

  CRYSTALS 9 2 2019年02月 [査読有り][通常論文]
   

  Thermodynamic picture induced by pi-d interaction in a molecular magnetic superconductor kappa-(BETS)(2)FeX4 (X = Cl, Br), where BETS is bis(ethylenedithio)tetraselenafulvalene, studied by single crystal calorimetry is reviewed. Although the S = 5/2 spins of Fe3+ in the anion layers form a three-dimensional long-range ordering with nearly full entropy of Rln6, a broad hump structure appears in the temperature dependence of the magnetic heat capacity only when the magnetic field is applied parallel to the a axis, which is considered as the magnetic easy axis. The scaling of the temperature dependence of the magnetic heat capacity of the two salts is possible using the parameter of |J(dd)|/k(B) and therefore the origin of the hump structure is related to the direct magnetic interaction, J(dd), that is dominant in the system. Quite unusual crossover from a three-dimensional ordering to a one-dimensional magnet occurs when magnetic fields are applied parallel to the a axis. A notable anisotropic field-direction dependence against the in-plane magnetic field was also observed in the transition temperature of the bulk superconductivity by the angle-resolved heat capacity measurements. We discuss the origin of this in-plane anisotropy in terms of the 3d electron spin configuration change induced by magnetic fields.
• Multistep Development of the Hyperfine Fields in lambda-(BEDT-STF)(2)FeCl4 Studied by Mossbauer Spectroscopy

  Fukuoka Shuhei, Sawada Masashi, Minamidate Takaaki, Matsunaga Noriaki, Nomura Kazushige, Ihara Yoshihiko, Kawamoto Atsushi, Doi Yoshihiro, Wakeshima Makoto, Hinatsu Yukio

  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 87 9 2018年09月15日 [査読有り][通常論文]
   

  We have investigated the magnetic properties of lambda-(BEDT-STF)(2) FeCl4 by Mossbauer measurement to reveal the origin of the paramagnetic-like behavior of the 3d spin system observed in lambda-(BEDT-STF)(2) FeCl(4 )using the donor substitution effect. We found that the temperature dependence of the hyperfine fields shows multistep development below T-N of 16K. From comparison of the Mossbauer results and a theoretical model, we demonstrated that the multistep development is caused by coupling between the 3d spins and the pi spins with strong spin correlation. We propose that the multistep development of the hyperfine fields is an intrinsic behavior induced by the pi-d interaction.
• Coupling of molecular motion and electronic state in the organic molecular dimer Mott insulator β′ -(BEDT-TTF) 2ICl2

  Masashi Sawada, Shuhei Fukuoka, Atsushi Kawamoto

  Physical Review B 97 4 2018年01月19日 [査読有り][通常論文]
   

  We have performed H1 NMR and C13 NMR measurements to investigate the coupling between molecular dynamics and the electronic state of β′-(BEDT-TTF)2ICl2. From the H1 NMR measurements, we observed a frequency-dependent anomaly in the nuclear spin-lattice relaxation rate T1-11 that originates from the slowing down of the ethylene motion. In the C13 NMR measurements, we found an anomaly in the linewidth of the NMR spectra at around 150 K, which is attributed to a nuclear spin-spin relaxation rate (T213) anomaly. The magnitudes of the anomalies in the linewidth and in T2-113 are related to the hyperfine coupling constant. These results suggest that the ethylene motion modulates the molecular orbital of the BEDT-TTF molecules and gives rise to a difference in the orbital energy between the "staggered" and "eclipsed" conformations. We propose that significant coupling exists between the ethylene motion and the electronic state of the molecular dimer and that the ethylene dynamics can trigger the emergence of charge degrees of freedom inside the dimers and cause the dielectric anomaly in β′-(BEDT-TTF)2ICl2.
• Antiferromagnetic ordering in organic conductor λ-(BEDT-TTF)2GaCl4 probed by 13CNMR

  Yohei Saito, Shuhei Fukuoka, Takuya Kobayashi, Atsushi Kawamoto, Hatsumi Mori

  Journal of the Physical Society of Japan 87 1 2018年 [査読有り][通常論文]
   

  The ground state of λ-(BEDT-TTF)2GaCl4, which has the same structure as the organic superconductor λ-(BETS)2-GaCl4, was investigated by magnetic susceptibility and 13C NMR measurements. The temperature dependence of the magnetic susceptibility revealed an antiferromagnetic (AF) correlation with J/kB ∼ 98 K. NMR spectrum splitting and the divergence of 1=T1 were observed at approximately 13 K, which is associated with the AF transition. We found that the AF structure is commensurate according to discrete NMR peak splitting, suggesting that the ground state of λ- (BEDT-TTF)2GaCl4 is an AF dimer-Mott insulating state. Our results suggest that the superconducting phase of λ-type salts would be located near the AF insulating phase.
• Anisotropic Field Dependence of the Superconducting Transition in the Magnetic Molecular Superconductor kappa-(BETS)(2)FeBr4

  Shuhei Fukuoka, Satoshi Yamashita, Yasuhiro Nakazawa, Takashi Yamamoto, Hideki Fujiwara

  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 86 1 2017年01月 [査読有り][通常論文]
   

  Angle-resolved heat capacity measurements of a pi-d interacting system of kappa-(BETS)(2)FeBr4 [BETS = bis(ethylene-dithio) tetraselenafulvalene] with in-plane magnetic fields are performed. We observed a thermal anomaly in association with the superconducting transition of the pi electrons in the pi-d compound for the first time. By pursuing a systematic change in the thermal anomaly, we found that the thermodynamic feature of the superconducting state shows large anisotropy against in-plane magnetic fields. When the field is applied parallel to the c-axis, the thermal anomaly remains up to 2.6 T with a distinct peak structure. On the other hand, it is suppressed in synchrony with the decrease of the antiferromagnetic transition temperature, when the field is applied parallel to the a-axis. Our thermodynamic results indicate that the effect of the pi-d interaction appears even when the pi electrons are itinerant and that the anisotropic field-direction dependence of the superconducting transition originates from the correlation between superconductivity and magnetism.
• Thermodynamic properties of antiferromagnetic ordered states of pi-d interacting systems of kappa-(BETS)(2)FeX4(X = Br, Cl)

  Shuhei Fukuoka, Satoshi Yamashita, Yasuhiro Nakazawa, Takashi Yamamoto, Hideki Fujiwara, Takashi Shirahata, Kazuko Takahashi

  PHYSICAL REVIEW B 93 24 2016年06月 [査読有り][通常論文]
   

  The results are presented for systematic heat capacity measurements of pi-d interacting systems of kappa-(BETS)(2)FeBr4 and kappa-(BETS)(2)FeCl4 [BETS = bis(ethylenedithio)tetraselenafulvalene] performed under in-plane magnetic fields. We observed sharp thermal anomalies at 2.47 K for kappa-(BETS)(2)FeBr4 and at 0.47 K for kappa-(BETS)(2)FeCl4 at 0 T that are associated with antiferromagnetic transitions of the 3d electrons in the anion layers. From analyses of the magnetic heat capacity data, we indicate that the two compounds show unconventional thermodynamic behaviors inherent in the pi-d interacting layered system. In the case of kappa-(BETS)(2)FeBr4, a small hump structure was observed in the magnetic heat capacity below the transition temperature when a magnetic field was applied parallel to the a axis. In the case of kappa-(BETS)(2)FeCl4, a similar hump structure was observed at 0 T that remained in the data with magnetic fields applied parallel to the a axis. We demonstrate that the temperature dependencies of the magnetic heat capacities scale well by normalizing the temperatures with dominant one-dimensional direct interactions (J(dd)/k(B)) of each compound. The field dependencies of the transition temperatures and the hump structures are elucidated in one simple magnetic field vs temperature (H-T) phase diagram. These results indicate that the thermodynamic features of both kappa-type BETS salts are essentially equivalent, and the observed hump structures are derived from the one-dimensional J(dd) interaction characters, which are still influential for magnetic features even in the long-range magnetic ordered states.
• Construction of relaxation calorimetry for 10(1-2) mu g samples and heat capacity measurements of organic complexes

  Shusaku Imajo, Shuhei Fukuoka, Satoshi Yamashita, Yasuhiro Nakazawa

  JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 123 3 1871 - 1876 2016年03月 [査読有り][通常論文]
   

  We report design and constructional details of a small-sized sample stage for relaxation calorimetry by utilizing commercially available ruthenium oxide chip sensors. The reduction in addenda heat capacity attained by fabrication of chip sensors made it possible to measure absolute values of the heat capacity of molecular compounds weighing in an order of 10(1-2) mu g with better temperature resolution. The result of calibration of the system by measuring 54.0 mu g metal indium which shows superconductive transition at 3.2 K is presented in the former part. Upon determining thermodynamic parameters of gamma and beta corresponding to the electronic heat capacity coefficient and the lattice heat capacity coefficient, respectively, we confirm that accurate measurements by such small amount of sample are possible. The magnitude of heat capacity jump is also discussed by comparing 0 T data and those under magnetic fields. Using this new calorimetry system, we then measured heat capacity of kappa-type organic superconductive salts of kappa-(BEDT-TTF)(2)Cu(NCS)(2) and kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br down to 0.7 K and discuss the nodal feature of the superconductive gap in them in the latter part. Measurements down to He-3 temperature region with external magnetic fields will be possible for various organic conducting systems by a single piece of a crystal.
• Cooling-rate-controlled heat capacity measurements of organic superconductor (TMTSF)(2)ClO4

  Satoshi Morishita, Ryo Yoshimoto, Shuhei Fukuoka, Satoshi Yamashita, Hiroki Akutsu, Yasuhiro Nakazawa

  JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 123 3 1877 - 1881 2016年03月 [査読有り][通常論文]
   

  An experimental technique for controlling cooling rate at low-temperature region in the heat capacity measurements was developed, and results of the heat capacity measurements of organic superconductor (TMTSF)(2)ClO4 cooled down with various cooling rates are presented. We succeeded in obtaining heat capacity data for a single piece of a crystal down to 0.7 K to study electronic states attained with slow cooling rates to extremely high cooling rate up to 500 K min(-1). In the case of slow cooling at 0.17 K min(-1), we observed a distinct peak of the superconductive transition which is almost consistent with previous results. The fraction of superconductive part is reduced in faster cooling rates, and no distinct peak structure in C (p) T (-1) versus T (2) plot is observed around T (c) in the data of higher rate than 1.3 K min(-1). In the rapid cooling region of 200 K min(-1), clear reduction in electron density of states reflected in the change of the normal state gamma value in the electronic heat capacity was observed. The sample shows an insulating character with a charge gap in the case of rapid cooling of 500 K min(-1). We also discuss the feature of thermal anomaly related to the anion ordering around 24 K. A kind of glass-like freezing in residual conformational dynamics is suggested from the step-like decrease in C (p) T (-1) around 19 K.
• 一軸圧下NMR実験によるα-(BEDT-TTF)₂RbHg(SCN)₄の電荷密度波相と超伝導相の研究

  大沼 晃浩, 熊谷 浩也, 藁谷 拓実, 小林 拓矢, 斎藤 洋平, 福岡 脩平, 井原 慶彦, 河本 充司

  日本物理学会講演概要集 71 1675 - 1675 一般社団法人 日本物理学会 2016年 

  電荷密度波相近傍に超伝導が見つかっている物質として\alpha-(BEDT-TF)_2_MHg(SCN)_4_ (M=K，Rb，NH_4_)がある。Rb塩はT_CDW_=12 Kで電荷密度波転移し、NH_4_塩はT_C_=1.5 Kで超伝導転移する。二つの塩の関係は一軸圧法で調べられており、c軸圧により超伝導が誘起されることが示唆されている。超伝導の誘起に伴う電子状態の変化を観測するために、Rb塩を対象にc軸圧下NMR測定を行った。

• Electronic Structure and the Properties of Phosphorene and Few-Layer Black Phosphorus

  Shuhei Fukuoka, Toshihiro Taen, Toshihito Osada

  JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 84 12 2015年12月 [査読有り][通常論文]
   

  A single atomic layer of black phosphorus, phosphorene, was experimentally realized in 2014. It has a puckered honeycomb lattice structure and a semiconducting electronic structure. In the first part of this paper, we use a simple LCAO model, and qualitatively discuss the electronic structure of phosphorene systems under electric and magnetic fields, especially noting their midgap edge states. The next part is devoted to the review of the progress in research on phosphorene over the past one year since its realization in 2014. Phosphorene has been a typical material to study the semiconductor physics in atomic layers.
• Heat Capacity of Spin Liquid System of EtMe3Sb[Pd(dmit)2]2

  Yamashita Satoshi, Yoshimoto Ryo, Fukuoka Shuhei, Nakazawa Yasuhiro, Kato Reizo

  Quantum Matter 4 4 314 - 318 2015年08月 [査読有り][通常論文]
  
• Investigations on Electronic States of Molecule-based Compounds by High-Pressure AC Calorimetry

  Nakazawa Yasuhiro, Yoshimoto Ryo, Fukuoka Shuhei, Yamashita Satoshi

  Current Inorganic Chemistry 4 2 122 - 134 2014年04月 [査読有り][通常論文]
  
• Magnetic transition in dimerized radical cation salt of (BPDT-TTF)(2)ICl2 studied by heat capacity measurements

  Guoyang Guan, Shuhei Fukuoka, Satoshi Yamashita, Takashi Yamamoto, Hiromi Taniguchi, Yasuhiro Nakazawa

  JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 113 3 1197 - 1201 2013年09月 [査読有り][通常論文]
   

  Thermodynamic investigation using the relaxation calorimetry technique and the microchip calorimetry technique is performed to clarify low-temperature behaviors of a radical cation salt consisting of a donor molecule of bispropylenedithiotetrathiafulvalene (BPDT-TTF) and a linear anion of . This compound has a layered structure similar to numerous BEDT-TTF compounds. The donor molecules form a dimerized arrangement in the layer. Temperature dependence of heat capacity obtained by the relaxation technique shows a broad hump structure around 20-25 K corresponding to the temperature where the magnetic susceptibility shows a drastic decrease due to the formation of the singlet spin state. The microchip calorimetry technique detected a step-like anomaly around 23 K in the temperature dependence of C (p) T (-1) of which entropy is evaluated as only few % of Rln2 corresponding to the full entropy of localized pi-electrons located on each dimer unit. The negligibly small T-linear term in the low-temperature heat capacity and absence of magnetic fields dependence below 3.2 K predict opening of rigid gap structure in the spin excitations, which is consistent with a spin-singlet formation due to the formation of spin-Peierls type ordering or charge ordering state.
• Development of heat capacity measurement system for single crystals of molecule-based compounds

  Shuhei Fukuoka, Yuki Horie, Satoshi Yamashita, Yasuhiro Nakazawa

  JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 113 3 1303 - 1308 2013年09月 [査読有り][通常論文]
   

  We report on construction of a new low temperature heat capacity measurement system. This system was designed for performing thermodynamic investigation by thermal relaxation technique for small amount of samples at extremely low temperature region between 70 mK and 10 K. Two different calorimetry cells for this system were designed. One is a usual-type calorimetry cell consisting of tiny chip-type thermometer and strain gauge heater. The size of the sample stage has been reduced for measuring small samples. The other is designed for performing heat capacity measurements under magnetic fields of which magnitude and direction are accurately controlled. The calorimetry cells with heat capacity measurement unit can be mounted on a handy top-loading type dilution refrigerator of which outer diameter including the adiabatic space is 27 mm. We discuss basic performance and specification of the constructed cells and low temperature heat capacity data of an organic charge transfer salt obtained by this system.
• Magnetic heat capacities of kappa-(BETS)(2)FeBr4 measured by a micro-chip calorimeter

  Shuhei Fukuoka, Satoshi Yamashita, Takashi Yamamoto, Yasuhiro Nakazawa, Akiko Kobayashi, Hayao Kobayashi

  PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 5 9 5 1174 - 1176 2012年 [査読有り][通常論文]
   

  Low temperature thermodynamic properties of kappa-(BETS)(2)FeBr4 are studied by using a tiny single crystal sample with 1 mu g adhered on a micro-chip calorimeter TCG3880. A large thermal anomaly associated with the antiferromagnetic transition of localized d electrons of Fe3+ was observed around 2.2 K. With the increase of magnetic fields applied parallel to the ac plane, the transition temperature shifts to lower temperature side accompanied by an anisotropic character. We found that the reduction of the transition temperature is largest, when magnetic field was applied parallel to a-axis. This observation is consistent with the previous result obtained by transport measurements which claimed that the spin easy axis is a-axis. The results demonstrate that the microchip calorimeter is effective for conducting thermodynamic measurements of molecular compounds. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
• Heat capacity measurements of chiral and racemic molecular magnets

  Shuhei Fukuoka, Satoshi Yamashita, Takashi Yamamoto, Yasuhiro Nakazawa, Hiroyuki Higashikawa, Katsuya Inoue

  PHYSICA B-CONDENSED MATTER 405 11 S19 - S22 2010年06月 [査読有り][通常論文]
   

  Thermodynamic nature of the magnetic transitions of a cyano-bridged W(V)-Cu(II) compound of [W(CN)(8)](4)[Cu(pn)H(2)O](4)[Cu(pn)](2) 2 5H(2)O is studied by low-temperature heat capacity measurements Distinct thermal anomalies were observed in the temperature dependence of the heat capacity at 7 8 K for chiral compound (S-enantiomer) and 7 2 K for racemic compound They are associated with the antiferromagnetic transitions reported by the previous magnetization measurements In the case of S-enantiomer a shoulder structure of C(p)/T has been observed just below the main peak of the antiferromagnetic transition temperature at 0 T The shoulder grows to a sharp anomaly with a first order character by applying magnetic field of about 1 T in the b-axis direction On the other hand just a broadening of the peak was observed for racemic compound which means that the complicated behavior under magnetic field is derived from the crystallographic chirality We also studied the behavior of S-enantiomer with magnetic fields applied parallel to the c-axis and found that the first order transition is not induced Appearance of the complicated peak structure including the first order character specific in the b-direction is ascribed to peculiar magnetic ordering derived from crystallographic chirality related to the Dzyaloshinskii-Moriya (DM) interaction (C) 2010 Elsevier B V All rights reserved
• Low-temperature heat capacity measurements of x-type organic superconductors under pressure

  N. Tokoro, S. Fukuoka, O. Kubota, Y. Nakazawa

  PHYSICA B-CONDENSED MATTER 405 11 S273 - S276 2010年06月 [査読有り][通常論文]
   

  Thermodynamic measurements using single crystals of K-type organic superconductors have been performed under pressure and with magnetic field We have adopted the ac temperature modulation technique for detecting relative variation of heat capacity as a function of temperature since usual adiabatic condition inevitable for getting absolute values of heat capacities is difficult to attain under pressure We used small ruthenium oxide chips as a heater and a thermometer and adhered them on the both side of single crystal and put them inside the Cu-Be cramp type pressure cell The broad hump structure around 9K which may be attributable to the thermal anomaly related to the superconductive transition was observed in kappa-(BEDT-TTF)(2)Cu(NCS)(2) However the worse sensitivity of ruthenium oxide sensor (100 Omega at room temperature) in this temperature region make it difficult to separate the peak from the large background contribution In the case of kappa-[(BEDT-TTF)(0) (9)(BEDSe-TTF)(0) (1)](2)Cu[N(CN)(2)]Br we have observed a sharp peak in the heat capacity at ambient pressure and its downward shift at 3 kbar The application of magnetic fields in the parallel direction to the superconductive layers was found to suppress the peak structure The behaviors are consistent with the typical nature of 2D superconductors and the electronic phase diagram of K-type organic salts (C) 2010 Elsevier B V All rights reserved
• Thermodynamic investigation of coordination-networked systems of [Mn-4] single-molecule magnets under pressure

  O. Kubota, S. Fukuoka, Y. Nakazawa, K. Nakata, M. Yamashita, H. Miyasaka

  JOURNAL OF PHYSICS-CONDENSED MATTER 22 2 2010年01月 [査読有り][通常論文]
   

  Low temperature heat capacity measurements under pressure were performed for tiny single crystals of two-dimensional coordination-networked compounds consisting of [Mn-4] single-molecule magnets (SMMs) by the ac temperature modulation technique. Systematic variations of the peak temperature and the peak width of the thermal anomalies produced by pressure were clearly detected using two ruthenium oxide resistance chips in the Cu-Be clamp-type cell. A linear increase of the Neel temperature for an ordering set of large SMM spins with S = 9 was observed in [Mn-4(hmp)(6){N(CN)(2)}(2)](ClO4)(2), while a non-monotonic variation of the peak temperatures and peak shapes was observed in [Mn-4(hmp)(4)Br-2(OMe)(2) {N(CN)(2)}(2)](ClO4)(2)center dot 2THF center dot 0.5H(2)O (hmp(-) = 2-hydroxymethylpyridinate; N(CN)(2) = dicyanamide as the linker among SMMs). We also report on thermodynamic behavior produced by changing external pressures and magnetic fields. The results are discussed in terms of the tilting angle of Ising axes in the two-dimensional plane.

講演・口頭発表等

• 69/71Ga NMRからみたλ-(BEDT-STF)2GaCl4の低温磁気状態

  福岡脩平, 伊藤悠馬, 井原慶彦, 河本充司

  日本物理学会2021年秋季大会 2021年09月
• λ-(BEDT-STF)2FexGa1-xCl4における磁気秩序の安定化

  伊藤悠馬, 春山和希, 福岡脩平, 井原慶彦, 河本充司

  日本物理学会第76回年次大会 2021年03月
• λ-(BEST)2GaCl4 塩の 69,71Ga-NMR

  河本充司, 福岡脩平, 小川巧真, 伊藤悠馬, 伊藤有咲, 小林拓矢, 谷口弘三

  日本物理学会第76回年次大会 2021年03月
• π-d系物質λ-(BEDT-STF)2FeCl4の誘電特性

  福岡脩平, 伊藤悠馬, 高橋仁徳, 松永悟明, 井原慶彦, 河本充司

  日本物理学会2020年秋季大会 2020年09月
• λ-(BEDT-STF)2FexGa1-xCl4混晶系の相図と内部磁場

  福岡脩平, 春山和希, 井原慶彦, 河本充司

  日本物理学会第75回年次大会 2020年03月
• 有機分子を挿入したTTF-CA類縁体の電子状態

  三枝大輔, 福岡脩平, 井原慶彦, 河本充司, 高橋幸裕, 竹久美佳, 田中恵里, 原田潤, 稲辺保

  日本物理学会2019年秋季大会 2019年09月
• λ-(BEDT-STF)2FexGa1-xCl4混晶系の磁気状態

  福岡脩平, 春山和希, 井原慶彦, 河本充司

  日本物理学会2019年秋季大会 2019年09月
• λ-(BEDT-STF)2FeCl4の磁気秩序状態に関する熱的研究

  福岡脩平, 南舘孝亮, 松永悟明, 野村一成, 井原慶彦, 河本充司

  日本物理学会第74回年次大会 2019年03月
• 13C NMR測定によるπ-d系物質λ-(BEDT-STF)2FeCl4の低温磁気状態の研究  [通常講演]

  福岡脩平, 南舘孝亮, 松永悟明, 野村一成, 井原慶彦, 河本充司

  日本物理学会 2018年秋季大会 2018年09月 口頭発表（一般）
• 13C NMRによるlambda-(BEDT-TTF)2GaCl4の圧力下の電子物性の研究  [通常講演]

  澤田賢志, 斉藤洋平, 福岡脩平, 河本充司

  日本物理学会 2018年秋季大会 2018年09月
• 誘電異常を示すTTF‐CA類縁体の温度圧力相図  [通常講演]

  福岡脩平, 石川貴子, 河本充司, 高橋幸裕, 竹久美佳, 田中恵里, 原田潤, 稲辺保

  日本物理学会講演概要集(CD-ROM) 2018年03月
• β′′‐(BEDT‐TTF)₄[(H₃O)Ga(C₂O₄)₃]・C₆H₅NO₂の電荷秩序相近傍における面間抵抗測定  [通常講演]

  森部一斗, 福岡脩平, 井原慶彦, 河本充司

  日本物理学会講演概要集(CD-ROM) 2018年03月
• β’‐(BEDT‐TTF)₂ICl₂における分子運動と電子状態  [通常講演]

  福岡脩平, 三枝大輔, 澤田賢志, 江頭由浩, 井原慶彦, 河本充司

  日本物理学会講演概要集(CD-ROM) 2017年09月
• ESR分光法によるβ′′‐(BEDT‐TTF)₄[(H₃O)Ga(C₂O₄)₃]・C₆H₅NO₂の電荷秩序の観測  [通常講演]

  井原慶彦, 福岡脩平, 河本充司

  日本物理学会講演概要集(CD-ROM) 2017年09月
• π‐d系物質λ‐(STF)₂FeCl₄のメスバウアー測定  [通常講演]

  福岡脩平, 澤田賢志, 南舘孝亮, 河本充司, 土井貴弘, 分島亮, 日夏幸雄

  日本物理学会講演概要集(CD-ROM) 2017年03月 

  \lambda-(BETS)_2_FeCl_4_はd電子に強い\pi-d相互作用が働くにもかかわらず、低温まで常磁性的挙動を示す異常磁気状態を示す。この異常磁気状態の発現には、\pi電子系が低温で示す金属絶縁体転移が重要とされているが、その起源は未解明である。\lambda-(STF) _2_FeCl_4_は\lambda-(BETS) _2_FeCl_4_と同型の塩でありながら、\pi電子系は室温から絶縁体であるため、金属絶縁体転移を伴わない場合のd電子系の低温磁気状態を議論することができる。本研究では、\lambda-(STF) _2_FeCl_4_の^57^Feメスバウアー測定を行い、\lambda-(STF) _2_FeCl_4_の磁気状態について調べた。

• 一軸圧力下NMR実験によるα‐(BEDT‐TTF)₂MHg(SCN)₄の電荷密度波相と超伝導相の研究  [通常講演]

  大沼晃浩, 熊谷浩也, 藁谷拓実, 小林拓矢, 齋藤洋平, 福岡脩平, 井原慶彦, 河本充司

  日本物理学会講演概要集(CD-ROM) 2016年09月
• イオン液体トランジスタを用いた層状強相関物質NiGa₂S₄への電界効果  [通常講演]

  福岡脩平, 田縁俊光, 長田俊人, 肥後友也, 中辻知

  日本物理学会講演概要集(CD-ROM) 2015年09月
• 層状強相関物質AGa₂S₄(A=Ni,Fe)超薄膜における電界効果  [通常講演]

  福岡脩平, 長田俊人, 肥後友也, 中辻知

  日本物理学会講演概要集(CD-ROM) 2015年03月
• κ‐(BETS)₂FeBr₄の超伝導状態の熱的研究  [通常講演]

  福岡脩平, 山下智史, 中澤康浩, 山本貴, 藤原秀紀

  日本物理学会講演概要集 2014年03月
• 磁性伝導体BETS塩の磁場制御下熱測定  [通常講演]

  福岡脩平, 山下智史, 中澤康浩, 山本貴, 白旗崇, 藤原秀紀, 高橋かず子

  熱測定討論会講演要旨集 2013年10月
• 重水素置換したX[Pd(dmit)₂]₂の低温熱容量  [通常講演]

  山下智史, 福岡脩平, 中澤康浩, 上田康平, CUI Hengbo, 山本浩史, 加藤礼三

  日本物理学会講演概要集 2013年08月
• π‐d系分子性導体BETS塩の低温電子状態  [通常講演]

  福岡脩平, 山下智史, 中澤康浩, 藤原秀紀, 山本貴, 白旗崇, 高橋かず子

  日本物理学会講演概要集 2013年08月
• π‐d系分子性導体BETS塩の面内磁場下熱測定  [通常講演]

  福岡脩平, 山下智史, 山本貴, 中澤康浩, 藤原秀紀, 白旗崇, 高橋かず子

  日本物理学会講演概要集 2013年03月
• X[Pd(dmit)₂]₂系における量子スピン液体‐電荷秩序近傍の低温熱挙動  [通常講演]

  山下智史, 福岡脩平, 中澤康浩, 上田康平, CUI Hengbo, 山本浩史, 加藤礼三

  日本物理学会講演概要集 2013年03月
• 自作熱量計によるκ型有機超伝導体の精密角度分解比熱測定  [通常講演]

  今城周作, 福岡脩平, 山下智史, 中澤康浩

  分子科学討論会講演プログラム&要旨(Web) 2013年
• 面内磁場下におけるκ‐(BETS)₂FeX₄(X=Cl,Br)の熱的研究  [通常講演]

  福岡脩平, 山下智史, 山本貴, 中澤康浩, 藤原秀紀, 白旗崇, 高橋かず子, 小林速男, 小林昭子

  日本物理学会講演概要集 2012年08月
• 20aEB-3 Et_2Me_2As_xSb_<1-x>[Pd(dmit)_2]_2におけるギャップレスな量子スピン液体状態(20aEB π-d系(dmitなど),領域7(分子性固体・有機導体))  [通常講演]

  山下 智史, 福岡 脩平, 中澤 康浩, 上田 康平, 山本 浩史, 加藤 礼三

  日本物理学会講演概要集 2012年08月
• (Me₄Sb)_x(EtMe₃Sb)_1-x[Pd(dmit)₂]₂混晶系のギャップレス励起に関する熱的研究  [通常講演]

  山下智史, 福岡脩平, 中澤康浩, 上田康浩, CUI Hengbo, 福永武男, 山本浩史, 加藤礼三

  日本物理学会講演概要集 2012年03月
• π‐d系有機導体κ‐(BETS)₂FeX₄(X=Cl,Br)の磁場下熱容量測定  [通常講演]

  福岡脩平, 山本貴, 中澤康浩, 白旗崇, 高橋かず子, 小林速男, 小林昭子

  日本物理学会講演概要集 2012年03月
• プルシアンブルー型錯体の熱容量測定  [通常講演]

  川本結加, 堀江裕樹, 福岡脩平, 中澤康浩, MILLER Joel S

  熱測定討論会講演要旨集 2011年10月
• [Cu(acac)(OCH₃)]₂の熱容量測定  [通常講演]

  吉住昌将, 福岡脩平, 山本貴, 中澤康浩

  熱測定討論会講演要旨集 2011年10月
• 熱容量測定によるキラル磁性体の磁気転移の研究  [通常講演]

  福岡脩平, 山本貴, 中澤康浩, 東川大志, 井上克也

  熱測定討論会講演要旨集 2011年10月
• ナノグラファイトの低温熱容量  [通常講演]

  堀江裕樹, 福岡脩平, 中澤康浩, 高井和之, 榎敏明

  熱測定討論会講演要旨集 2011年10月
• Volborthite(Cu₃V₂O₇(OH)₂・2H₂O)の低温熱容量測定  [通常講演]

  森下知志, 堀江裕樹, 福岡脩平, 中澤康浩, 廣井善二

  熱測定討論会講演要旨集 2011年10月
• X[Pd(dmit)₂]₂混晶塩系におけるスピン液体‐隣接相境界に関する熱的研究  [通常講演]

  山下智史, 福岡脩平, 中澤康浩, CUI Hengbo, 福永武男, 加藤礼三

  日本物理学会講演概要集 2011年08月
• キラル金属磁性錯体の磁場下熱容量測定  [通常講演]

  福岡脩平, 山本貴, 中澤康浩, 東川大志, 井上克也

  日本物理学会講演概要集 2011年03月
• κ‐(BETS)₂FeBr₄の熱容量の磁場印加方向依存性  [通常講演]

  福岡脩平, 山本貴, 中澤康浩, 小林昭子, 小林速男

  日本物理学会講演概要集 2010年03月
• 熱容量測定による有機導体BETS塩の低温物性研究  [通常講演]

  福岡脩平, 山下智史, 山本貴, 中澤康浩, 小林昭子, 小林速男, 薬師久彌

  熱測定討論会講演要旨集 2009年09月

その他活動・業績

• π-d系物質λ-(BEDT-STF)₂FeCl₄の誘電特性

  福岡脩平, 伊藤悠馬, 高橋仁徳, 松永悟明, 井原慶彦, 河本充司 日本物理学会講演概要集(CD-ROM) 75 (2) 2020年
• 有機超伝導体における強磁場中異常超伝導状態の微視的研究

  井原慶彦, 福岡脩平, 河本充司, GOMES‐GARCIA Carlos J, 佐々木孝彦 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 2016 55 2017年06月 [査読無し][通常論文]
  
• 分子性磁性超伝導体の外部磁場に対する精密角度分解熱測定

  福岡脩平, 中澤康浩 熱測定 42 (1) 10 -16 2015年01月30日 [査読無し][通常論文]
  
• 磁性超伝導体κ‐BETS₂FeBr₄の超伝導転移温度の面内異方性

  福岡脩平, 中澤康浩 阪大化学熱学レポート (35) 112 -113 2014年12月 [査読無し][通常論文]
  
• 27pBC-8 κ-(BETS)_2FeBr_4の超伝導状態の熱的研究(27pBC π-d系(BETS)・磁性・超伝導,領域7(分子性固体))

  福岡 脩平, 山下 智史, 中澤 康浩, 山本 貴, 藤原 秀紀 日本物理学会講演概要集 69 (1) 832 -832 2014年03月05日
• BETS塩の示す磁気転移の熱的検証

  福岡脩平, 中澤康浩 阪大化学熱学レポート (34) 84 -85 2013年12月 [査読無し][通常論文]
  
• 有機超伝導体の角度分解電子比熱測定装置開発と評価

  今城周作, 福岡脩平, 中澤康浩 阪大化学熱学レポート (34) 58 -59 2013年12月 [査読無し][通常論文]
  
• 磁性超伝導体BETS塩の超伝導状態の熱的研究

  福岡脩平, 中澤康浩 阪大化学熱学レポート (34) 86 -87 2013年12月 [査読無し][通常論文]
  
• 28pXN-6 X[Pd(dmit)_2]_2系における量子スピン液体-電荷秩序近傍の低温熱挙動(28pXN π-d系(単一成分系,dmit系),領域7(分子性固体・有機導体))

  山下 智史, 福岡 脩平, 中澤 康浩, 上田 康平, 崔 亨波, 山本 浩史, 加藤 礼三 日本物理学会講演概要集 68 (1) 951 -951 2013年03月26日
• 低温下伝導面内磁場中における角度分解熱測定

  今城周作, 福岡脩平, 中澤康浩 阪大化学熱学レポート (33) 72 -73 2012年12月 [査読無し][通常論文]
  
• キラル磁性体の磁気転移の熱的性質

  福岡脩平, 中澤康浩 阪大化学熱学レポート (33) 56 -57 2012年12月 [査読無し][通常論文]
  
• π‐d相互作用をもつ有機電荷移動塩の磁場中熱容量

  福岡脩平, 中澤康浩 阪大化学熱学レポート (33) 58 -59 2012年12月 [査読無し][通常論文]
  
• 20aEB-3 Et_2Me_2As_xSb_<1-x>[Pd(dmit)_2]_2におけるギャップレスな量子スピン液体状態(20aEB π-d系(dmitなど),領域7(分子性固体・有機導体))

  山下 智史, 福岡 脩平, 中澤 康浩, 上田 康平, 山本 浩史, 加藤 礼三 日本物理学会講演概要集 67 (2) 784 -784 2012年08月24日
• 有機磁性超伝導体κ‐(BETS)₂FeCl₄の磁気相転移の熱力学的性質

  福岡脩平, 中澤康浩 阪大化学熱学レポート (32) 66 -67 2011年12月 [査読無し][通常論文]
  
• キラル磁性体の磁場誘起一次相転移

  福岡脩平, 中澤康浩 阪大化学熱学レポート (32) 64 -65 2011年12月 [査読無し][通常論文]
  
• 温度可変インサート中で使用可能なφ27mm希釈冷凍装置の整備と0.1‐10Kの連続熱容量測定

  福岡脩平, 堀江裕樹, 中澤康浩 阪大化学熱学レポート (32) 38 -39 2011年12月 [査読無し][通常論文]
  
• 分子研希釈冷凍機を用いた熱料量測定装置の開発と有機磁性超伝導体κ‐(BETS)₂FeCl₄の熱容量測定

  福岡脩平, 中澤康浩 阪大化学熱学レポート (31) 76 -77 2010年12月 [査読無し][通常論文]
  
• 分子研希釈冷凍機に組み込む低温熱測定ユニットの開発

  中澤康浩, 山下智史, 福岡脩平 阪大化学熱学レポート (30) 54 -55 2009年12月 [査読無し][通常論文]
  
• 磁場印加条件下でのキラル磁性体の磁気相転移

  福岡脩平, 山本貴 阪大化学熱学レポート (30) 82 -83 2009年12月 [査読無し][通常論文]
  
• 熱容量測定による有機導体BETS塩の低温物性研究

  福岡脩平, 山本貴 阪大化学熱学レポート (30) 90 -91 2009年12月 [査読無し][通常論文]
  

共同研究・競争的資金等の研究課題

• 非摂動磁場を用いた有機導体における電荷移動現象の制御と新物質相探索

  日本学術振興会：科学研究費助成事業

  研究期間 : 2024年04月 -2026年03月 

  代表者 : 福岡 脩平
• λ型有機導体のMott境界近傍の電子状態と磁場誘起絶縁体金属転移の解明

  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 : 2022年04月 -2025年03月 

  代表者 : 福岡 脩平
• 分子設計の自由度を活用したMott境界近傍に位置するλ型有機導体の電子状態の解明と物性探索

  日揮・実吉奨学会研究助成金：2022年度研究助成

  研究期間 : 2022年09月 -2024年08月
• 超分子チャンネル構造内での分子回転型水分子輸送機構の解明と高機能化

  クリタ水・環境科学振興財団：2022年度助成

  研究期間 : 2022年10月 -2023年09月
• 小型汎用パルス強磁場を用いた先端測定による強磁場物性開拓

  日本学術振興会：科学研究費補助金基盤研究B

  研究期間 : 2019年04月 -2023年03月 

  代表者 : 井原 慶彦
• 非対称なダイマー構造が誘起する新奇な電子状態の解明と機能開拓

  日本学術振興会：科学研究費補助金若手研究

  研究期間 : 2019年04月 -2022年03月 

  代表者 : 福岡 脩平
• 精密角度分解熱容量測定装置の開発と有機超伝導体及び量子磁性体への応用

  住友財団：基礎科学研究助成

  研究期間 : 2019年11月 -2020年11月 

  代表者 : 福岡 脩平
• dimer構造を持つ分子性固体が示す新奇誘電応答現象の探索と解明

  泉科学技術振興財団：2019年度研究助成金

  研究期間 : 2019年10月 -2020年09月 

  代表者 : 福岡 脩平
• Magnetic and thermodynamic properties of molecular p-d system l-(BEDT-STF)2FeCl4

  村田学術振興財団：研究者海外派遣援助

  研究期間 : 2019年09月 -2019年09月 

  代表者 : 福岡 脩平
• 多角的磁場制御下熱測定による分子性化合物の研究

  日本学術振興会：特別研究員奨励費（DC1)

  研究期間 : 2011年04月 -2014年03月 

  代表者 : 福岡 脩平

教育活動情報

主要な担当授業