Faculty Profiles - KOBAYASHI Tatsuo

Papers - KOBAYASHI Tatsuo

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Pressure-induced superconductivity emerging from antiferromagnetic phase in CeNiGe3 Reviewed

H Kotegawa, K Takeda, T Miyoshi, S Fukushima, H Hidaka, TC Kobayashi, T Akazawa, Y Ohishi, M Nakashima, A Thamizhavel, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 ( 4 ) 044713-1-6 2006.4

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

The antiferromagnet CeNiGe3 exhibits superconductivity under pressure. The Neel temperature initially increases with increasing pressure up to 3GPa and then becomes zero at a critical pressure (P-C) that is located at approximately 7GPa. We found that superconductivity emerges from 1.7 GPa in the antiferromagnetic (AF) phase removed from P-C. The superconductivity is realized in a wide pressure region including P-C. The coefficient A in the resistivity and the upper critical field (H,2) significantly change against pressure. A feature of CeNiGe3 is that the moderate heavy fermion state in the AF phase induces superconductivity.

DOI： 10.1143/JPSJ.75.044713

Anisotropic residual resistivity under high pressure in UIr Reviewed

Akihiro Hori, Hiroyuki Hidaka, Hisashi Kotegawa, Tatsuo C. Kobayashi, Teruhiko Akazawa, Syugo Ikeda, Etsuji Yamamoto, Yoshinori Haga, Rikio Settai, Yoshichika Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75 82 - 84 2006.1

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

Anisotropic resistivity in UIr has been investigated under high pressure. A huge enhancement of residual resistivity was found under high pressure for the measuring current parallel to the [0 1 0] direction while any anomalies were not observed in the resistivity for [1 0 (1) over bar]. The residual resistivity for [0 1 0] reduced to the original value in the pressure range where superconductivity appears. This anomalous behavior indicates that the ground state in the high-rho(0) state is not simple ferromagnet and the application of pressure induces the first-order transition to slightly different electronic state.

DOI： 10.1143/JPSJS.75S.82

Metastable sorption state of a metal-organic porous material determined by in situ synchrotron powder diffraction Reviewed

Yoshiki Kubota, Masaki Takata, Ryotaro Matsuda, Ryo Kitaura, Susumu Kitagawa, Tatsuo C. Kobayashi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 45 ( 30 ) 4932 - 4936 2006

Formation and characterization of crystalline molecular arrays of gas molecules in a 1-dimensional ultramicropore of a porous copper coordination polymer Reviewed

R Kitaura, R Matsuda, Y Kubota, S Kitagawa, M Takata, TC Kobayashi, M Suzuki

JOURNAL OF PHYSICAL CHEMISTRY B 109 ( 49 ) 23378 - 23385 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Molecules and atoms confined in a nanospace may have properties distinctly different from those of the bulk fluid, owing to the formation of a specific molecular array characteristic of nanospace. In situ synchrotron powder X-ray diffraction measurements have been used to observe confined guest molecules such as N(2), O(2), Ar, and CH(4) in the well-regulated ultramicropore of a copper coordination polymer, 1 ([Cu(2),(pzdc)(2)pyz]: pzdc = 2,3-pyrazinedicarboxylate and pyz = pyrazine). The obtained crystal structures indicate that guest molecules are confined in a linear fashion to form crystal ine-like regular ordered arrays, in contrast to the situation in the gas and liquid state, even at temperatures above the boiling point, and the ordered arrays are characteristic of the kind of gas molecule and the geometrical and potential properties of the ultramicropore of 1.

DOI： 10.1021/jp054411j

Change of the Fermi surface across the critical pressure in CeIn3: The de Haas-van Alphen study under pressure Reviewed

R Settai, T Kubo, T Shiromoto, D Honda, H Shishido, K Sugiyama, Y Haga, TD Matsuda, K Betsuyaku, H Harima, TC Kobayashi, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 11 ) 3016 - 3026 2005.11

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

We have studied a change of the Fermi surface in an antiferromagnet CeIn3 via the de Haas-van Alphen experiment under pressure up to 3 GPa. With increasing pressure P, the Neel temperature T-N = 10 K decreases and becomes zero at a critical pressure P-c similar or equal to 2.6 GPa. In the pressure region P > P,, we have observed a large main Fermi surface named a, which indicates that the electronic state of 4f electron in CeIn3 changes from localized to itinerant at P-c, as observed in the similar antiferromagnets CeRh2Si2 and CeRhIn5. The cyclotron effective mass m(c)(*) of this main Fermi surface is extremely enhanced around P-c: m(c)(*) similar or equal to 60m(0) at 2.7 GPa for the magnetic field along the (100) direction.

DOI： 10.1143/JPSJ.74.3016

Single crystal growth and fermi surface properties of an antiferromagnet UPdGa5 Reviewed

S Ikeda, TD Matsuda, Y Haga, E Yamamoto, M Nakashima, S Kirita, TC Kobayashi, M Hedo, Y Uwatoko, H Yamagami, H Shishido, T Ueda, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 8 ) 2277 - 2281 2005.8

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

We have succeeded in growing a high-quality single crystal of an antiferromagnet UPdGa5 by the Ga-flux method with the off-stoichiometric composition of U : Pd : Ga = 1 : 2 : 7.3. The Neel temperature T-N = 30.5 K is found to increase with increasing the residual resistivity ratio (RRR) and becomes constant for a high-quality single crystal sample whose RRR is larger than 50. The electronic state has been investigated by the de Haas-van Alphen experiment, indicating the similar cylindrical Fermi surfaces as in an antiferromagnet UPtGa5. We have also studied the pressure effect by measuring the electrical resistivity. The Neel temperature decreases with increasing pressure and becomes zero at 3.1 GPa. The antiferromagnetic state is changed into the paramagnetic state above 3.1 GPa.

DOI： 10.1143/JPSJ.74.2277

Heavy fermion compound SmOs4Sb12 in vicinity of ferromagnetic critical point Reviewed

H Kotegawa, H Hidaka, Y Shimaoka, T Miki, TC Kobayashi, D Kikuchi, H Sugawara, H Sato

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 8 ) 2173 - 2176 2005.8

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

We report nuclear quadrupole resonance (NQR) measurement at ambient pressure and resistivity measurement under high pressure in the new heavy fermion (HF) compound SmOs4Sb12. The NQR spectrum and the nuclear spin-lattice relaxation rate (1/T-1) clearly demonstrate the bulk nature of ferromagnetic ordering below T-C similar to 2 K. The temperature dependence of 1/T-1 exhibits the characteristic behaviors of a Kondo lattice. The application of pressure decreases Kondo temperature and stabilizes the magnetic ordering, which is the same tendency as that found in some Yb-based compounds. The obtained phase diagram indicates SmOs4Sb12 to be in the vicinity of its ferromagnetic critical point.

DOI： 10.1143/JPSJ.74.2173

Highly controlled acetylene accommodation in a metal-organic microporous material Reviewed

R Matsuda, R Kitaura, S Kitagawa, Y Kubota, RV Belosludov, TC Kobayashi, H Sakamoto, T Chiba, M Takata, Y Kawazoe, Y Mita

NATURE 436 ( 7048 ) 238 - 241 2005.7

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Metal - organic microporous materials(1-4) (MOMs) have attracted wide scientific attention owing to their unusual structure and properties, as well as commercial interest due to their potential applications in storage(5-9), separation(10,11) and heterogeneous catalysis(12,13). One of the advantages of MOMs compared to other microporous materials, such as activated carbons, is their ability to exhibit a variety of pore surface properties such as hydrophilicity and chirality, as a result of the controlled incorporation of organic functional groups into the pore walls(11,13-15). This capability means that the pore surfaces of MOMs could be designed to adsorb specific molecules; but few design strategies for the adsorption of small molecules have been established so far. Here we report high levels of selective sorption of acetylene molecules as compared to a very similar molecule, carbon dioxide, onto the functionalized surface of a MOM. The acetylene molecules are held at a periodic distance from one another by hydrogen bonding between two non-coordinated oxygen atoms in the nanoscale pore wall of the MOM and the two hydrogen atoms of the acetylene molecule. This permits the stable storage of acetylene at a density 200 times the safe compression limit of free acetylene at room temperature.

DOI： 10.1038/nature03852

De Haas-van Alphen effect in CeIn3 under pressure Reviewed

Rikio Settai, Tetsuo Kubo, Hiroaki Shishido, Tatsuo C. Kobayashi, Yoshichika Onuki

Physica B: Condensed Matter 359-361 317 - 319 2005.4

Language：English Publishing type：Research paper (international conference proceedings)

We have investigated a change of the electronic state in CeIn3 via de Haas-van Alphen (dHvA) experiments under pressure up to 2.72 GPa for the magnetic field along 〈110〉. A main Fermi surface with the dHvA frequency F=9.4×107 Oe and a large cyclotron mass mc*=53m0 was observed at 2.72 GPa in the vicinity of the critical pressure where the Néel temperature is suppressed to zero. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.119

Magnetization study of heavy Fermion superconductor URu2Si2 under high pressures Reviewed

K Tenya, Kawasaki, I, K Tameyasu, S Yasuda, M Yokoyama, H Amitsuka, N Tateiwa, TC Kobayashi

PHYSICA B-CONDENSED MATTER 359 1135 - 1137 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Magnetization measurements of URu2Si2 have been performed under hydrostatic pressures. The superconducting transition temperature decreases linearly with pressure up to 1.1 GPa and disappears above 1.5 GPa. The hysteretic magnetization shows characteristic behaviors at high pressures, suggesting that the pinning properties are changed due to the switch of the normal state to the antiferromagnetic state. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.325

Metal-insulator transition under high pressure in PrFe4P12 Reviewed

H Hidaka, Ando, I, H Kotegawa, TC Kobayashi, H Harima, M Kobayashi, H Sugawara, H Sato

PHYSICA B-CONDENSED MATTER 359 886 - 888 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have studied the electrical resistivity in a skutterudite compound PrFe4P12 under high pressure. An antiferroquadrupolar ordering temperature T-Q decreases monotonously with increasing pressure up to 2.4 GPa. Above 2.4 GPa, the metal-insulator (M-I) transition appears. By applying magnetic field, this M-I transition is suppressed easily and heavy-fermion state is realized. The observed Kondo effect and the field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions of the f electrons of Pr3+ survive even in the insulator phase. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.334

High-pressure effect on the electrical resistivity in CeNiGe3 and CeNi2Al5 Reviewed

M Nakashima, K Tabata, A Thamizhavel, TC Kobayashi, M Hedo, Y Uwatoko, K Shimizu, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 266 - 268 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have measured the electrical resistivity of antiferromagnetic Kondo compounds CeNiGe3 and CeNi2Al5 under pressure. In CeNiGe3, Neel temperature T-N initially increases with increasing pressure P up to 3 GPa, then decreases rather steeply with further increasing pressure, and becomes zero at a critical pressure P-c similar or equal to 5.5 GPa. The A and rho(0) values of the resistivity rho = rho(0) + AT(2) in the Fermi liquid relation become maximum around P-c. Superconductivity is found below 0.48 K in a wide pressure region from 4 to 10 GPa. In CeNi2Al5, the similar pressure dependence of TN is found, has a maximum at 3.9 GPa, and becomes zero around 6 GPa. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/i.physb.2005.01.066

Pressure-induced charge ordering of LiV2O4 Reviewed

K Takeda, H Hidaka, H Kotegawa, TC Kobayashi, K Shimizu, H Harima, K Fujiwara, K Miyoshi, J Takeuchi, Y Ohishi, T Adachi, M Takata, E Nishibori, M Sakata, T Watanuki, O Shimomura

PHYSICA B-CONDENSED MATTER 359 1312 - 1314 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The powder X-ray diffraction experiments of LiV2O4 have been performed at low temperature and high pressure using synchrotron radiation. In the isothermal experiment at 10 K, the cubic-rhombohedral phase transition corresponding to the metal-insulator transition is found at around 13 GPa. This transition seems to be due to charge ordering of V ions on the analogy of the metal-insulator transition in AlV2O4. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.390

Pressure-induced superconductivity in UIr without inversion symmetry Reviewed

T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki

PHYSICA B-CONDENSED MATTER 359 1138 - 1140 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of electrical resistivity and magnetization. The phase diagram consists of two ferromagnetic phases. The ferromagnetic phase FM1 with T-Cl similar to 46 K at ambient pressure disappears around 1.7 GPa. With further increase of pressure, the phase (FM2) with small ferromagnetic moment appears in the pressure range of P-Cl < P < 2.6 GPa. The superconducting phase exists near the disappearance point of the FM2 phase, indicating that the superconductivity is associated with the ferromagnetic critical fluctuation around P-C2. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2005.01.335

Pressure-induced metal-insulator transition in the filled skutterudite PrFe4P12 Reviewed

H Hidaka, Ando, I, H Kotegawa, TC Kobayashi, H Harima, M Kobayashi, H Sugawara, H Sato

PHYSICAL REVIEW B 71 ( 7 ) 2005.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

We have studied the electrical resistivity of the filled skutterudite compound PrFe4P12 under high pressure. The antiferroquadrupolar ordering temperature T-Q decreases monotonically with increasing pressure up to 2.4 GPa. Above 2.4 GPa, we have found that a metal-insulator (M-I) transition appears. The insulating state is easily suppressed by a magnetic field. The observed Kondo effect and a field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions survive in the insulating region. The quadrupolar interactions might play an essential role in the M-I transition. PrFe4P12 is an unusual compound in that it shows a pressure-induced transition from a metal to an insulator.

DOI： 10.1103/PhysRevB.71.073102

Pressure-induced metal-insulator transition in the filled skutterudite PrFe <inf>4</inf>P <inf>12</inf> Reviewed

Hiroyuki Hidaka, Ikuma Ando, Hisashi Kotegawa, Tatsuo C. Kobayashi, Hisatomo Harima, Miki Kobayashi, Hitoshi Sugawara, Hideyuki Sato

Physical Review B - Condensed Matter and Materials Physics 71 ( 7 ) 2005.2

Publishing type：Research paper (scientific journal)

We have studied the electrical resistivity of the filled skutterudite compound PrFe 4P 12 under high pressure. The antiferroquadrupolar ordering temperature T Q decreases monotonically with increasing pressure up to 2.4 GPa. Above 2.4 GPa, we have found that a metal-insulator (M-I) transition appears. The insulating state is easily suppressed by a magnetic field. The observed Kondo effect and a field-induced heavy-fermion state at high pressure suggest that the quadrupolar interactions survive in the insulating region. The quadrupolar interactions might play an essential role in the M-I transition. PrFe 4P 12 is an unusual compound in that it shows a pressure-induced transition from a metal to an insulator. ©2005 The American Physical Society.

DOI： 10.1103/PhysRevB.71.073102

Direct observation of hydrogen molecules adsorbed in a microporous coordination polymer Reviewed

Y. Kubota, M. Takata, R. Matsuda, R. Kitaura, S. Kitagawa, K. Kato, M. Sakata, T. C. Kobayashi

Angew. Chem. Int. Ed. 2005

Magnetic properties of molecular oxygen adsorbed in micro-porous metal-organic solids Reviewed

TC Kobayashi, A Matsuo, M Suzuki, K Kindo, R Kitaura, R Matsuda, S Kitagawa

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT ( 159 ) 271 - 279 2005

Language：English Publishing type：Research paper (scientific journal) Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE

The magnetic properties of O-2 adsorbed in nanochannels of porous metal-organic solids CPL-1 and CPL-p1 have been investigated by means of high-field magnetization process measurement. The contribution from adsorbed 02 shows the metamagnetic-like behavior in both compounds. We propose "the field-induced rearrangement mechanism" as the explanation for the metamagnetic-like behavior. It is known for the O-2-O-2 dimer that the magnetic interaction depends strongly on the intermolecular distance and the orientation of molecular axes. It is considered naturally that the stable arrangement with saturated magnetic moment in the sufficient high field is different from the H-structure which is stable at zero field.

DOI： 10.1143/PTPS.159.271

Guest shape-responsive fitting of porous coordination polymer with shrinkable framework Reviewed

R Matsuda, R Kitaura, S Kitagawa, Y Kubota, TC Kobayashi, S Horike, M Takata

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 126 ( 43 ) 14063 - 14070 2004.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

In situ synchrotron X-ray powder diffraction patterns of porous coordination polymers {[Cu-2-(pzdc)(2)(bpy)](.)G} have been measured (pzdc = pyrazine-2,3-dicarboxylate, bpy = 4,4'-bipyridine) (where G = H2O for CPL-2 superset of H2O, G = benzene for CPL-2 superset of benzene, and G = void for the apohost). The structures of apohost and CPL-2 superset of benzene were determined from Rietveld analysis. Adsorption of benzene in the channels induced a remarkable contraction in the crystal (b axis; 6.8%, volume; 4.9%), although the channels were occupied by the benzene molecules. This crystal transformation provides a new pore structure that is well suited for benzene molecules, and we denote it as a "shape-responsive fitting" transformation. This type of pore gives rise to a new guideline: frameworks can be composed of flexible motifs that are linked via strong bond and/or stiff motifs that are connected via weaker bonds.

DOI： 10.1021/ja046925m

Pressure-induced superconductivity in UIr Reviewed

T Akazawa, H Hidaka, H Kotegawa, TC Kobayashi, T Fujiwara, E Yamamoto, Y Haga, R Settai, Y Onuki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 73 ( 11 ) 3129 - 3134 2004.11

Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressure-temperature phase diagram has been investigated by means of the electrical resistivity and magnetization measurements under high pressure. The phase diagram consists of two magnetic phases, the Ising-like ferromagnetic phase (FM1) at low pressures and another magnetic phase (FM2) with the small ferromagnetic component along the [101] direction at high pressures. Superconductivity is observed in the narrow pressure range near the disappearance point of the FM2 phase, where the temperature dependence of resistivity follows the non-Fermi liquid form of T-1.6. From these experimental facts, the superconductivity is considered to be associated with the critical fluctuation with the disappearance of FM2 phase.

DOI： 10.1143/JPSJ.73.3129

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