理学博士, 東京大学

Natural sciences, Magnetism, superconductivity, and strongly correlated systems

Spin dynamics and antiferromagnetic order in PrBa2Cu4O8 studied by Cu nuclear resonance
Feb. 2003, Physical Review B, 67, 060404(R)

Spin dynamics and antiferromagnetic order in PrBa2Cu4O8 studied by Cu nuclear resonance
Feb. 2003, Physical Review B, 67, 060404(R)

Electronic structure of B-2p state in AIB(2) single crystal: Direct observation of p sigma and p pi density of states
J Nakamura; M Watanabe; T Oguchi; SY Nasubida; E Kabasawa; N Yamada; K Kuroki; H Yamazaki; S Shin; Y Umeda; S Minakawa; N Kimura; H Aoki
X-ray emission (XES) and absorption (XAS) spectra near the B-K edge were measured on single-crystalline AIB(2) compound which is an isostructural diboride of superconducting MgB2. The partial density of states (PDOS) of B-2psigma and ppi orbitals were derived from the polarization dependence of XES and XAS spectra. There are considerable amounts of PDOS near the Fermi energy in AIB(2) similarly to that in MgB2, but there are almost no PDOS in psigma orbitals of AIB(2) near the Fermi energy, i.e., a pseudo-gap in psigma state and a broad metallic state in ppi state are observed. The present result indirectly supports scenarios that the p(7 holes play an important role in the occurrence of superconductivity in MgB2. The overall features of PDOS were found to be in good agreement with the result of band calculation of AIB(2), but a small discrepancy in the Fermi energy is observed, which is attributed to the Al vacancy in the compounds, i.e., the estimated concentration is Al0.93B2., PHYSICAL SOC JAPAN, Feb. 2002, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 71, 2, 408-410, English, 0031-9015, 110001971557, WOS:000173986900010

Electronic structure of B-2p state in AIB(2) single crystal: Direct observation of p sigma and p pi density of states
J Nakamura; M Watanabe; T Oguchi; SY Nasubida; E Kabasawa; N Yamada; K Kuroki; H Yamazaki; S Shin; Y Umeda; S Minakawa; N Kimura; H Aoki
X-ray emission (XES) and absorption (XAS) spectra near the B-K edge were measured on single-crystalline AIB(2) compound which is an isostructural diboride of superconducting MgB2. The partial density of states (PDOS) of B-2psigma and ppi orbitals were derived from the polarization dependence of XES and XAS spectra. There are considerable amounts of PDOS near the Fermi energy in AIB(2) similarly to that in MgB2, but there are almost no PDOS in psigma orbitals of AIB(2) near the Fermi energy, i.e., a pseudo-gap in psigma state and a broad metallic state in ppi state are observed. The present result indirectly supports scenarios that the p(7 holes play an important role in the occurrence of superconductivity in MgB2. The overall features of PDOS were found to be in good agreement with the result of band calculation of AIB(2), but a small discrepancy in the Fermi energy is observed, which is attributed to the Al vacancy in the compounds, i.e., the estimated concentration is Al0.93B2., PHYSICAL SOC JAPAN, Feb. 2002, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 71, 2, 408-410, English, 0031-9015, 110001971557, WOS:000173986900010

軟X線吸収・発光分光によるMB_2(M=Mg,Al,Nb,Ta)のBの電子状態
Sep. 2001, 日本物理学会,徳島,2001.9.17-20

硼素K吸収端付近の軟X線吸収・発光分光による2硼化物の2p部分電子状態の研究
Sep. 2001, 日本物理学会,徳島,2001.9.17-20

Ca2+xY2-xCu5O10 のO-1s吸収端近傍のx 線吸収・発光分光
Mar. 2001, 日本物理学会第56回年次大会講演概要集第３分冊, 531

（Sr,Ca,La,Sr）14Cu24O41 の電子状態
Mar. 2001, 日本物理学会第56回年次大会講演概要集第３分冊, 531

"酸素１s発光分光測定によるPrBa₂Cu₄O₈単結晶の電子状態"
Mar. 2001, 日本物理学会講演概要集第３分冊, 524

Soft x-ray spectroscopy experiments on the near K-edge of B in MB$_2$ (M=Mg, Al, Ta and Nb)
2001, Physical Review B, 64, 174504 (1-4)

辺共有型CuO 鎖化合物のO1 s吸収端近傍のx 線吸収・発光分光
Jan. 2001, 第14回日本放射光学会年会・放射光科学合同シンポジュウム講演集, 247

（Sr,Ca,La,Sr)14Cu24O41 の酸素1s吸収端近傍のx線吸収・発光分光
Jan. 2001, 第14回日本放射光学会年会・放射光科学合同シンポジュウム講演集, 246

Study of YBa2Cu307-δ ceramic/Al interface
2001, Applied Surface Science, 169-170, 331-334

Soft x-ray spectroscopy experiments on the near K-edge of B in MB$_2$ (M=Mg, Al, Ta and Nb)
2001, Physical Review B, 64, 174504 (1-4)

Study of YBa2Cu307-δ ceramic/Al interface
2001, Applied Surface Science, 169-170, 331-334

Angle-Resolved Photoemission Study of Insulating and Metallic Cu-O Chains in PrBa2Cu307 an PrBa2Cu408
MIZOKAWA T; KIM C; INO A; GOTO M; TAGAMI M; YAMADA Y; HORII S; YAMADA N; HIRABAYASHI I
Nov. 2000, Phys. Rev. Lett., 85, 22, 4779-4782, 0031-9007, 11082650

Angle-Resolved Photoemission Study of Insulating and Metallic Cu-O Chains in PrBa2Cu307 an PrBa2Cu408
Nov. 2000, Phys. Rev. Lett., 85, 22, 4779-4782, 0031-9007, 11082650

高温超伝導体YBa₂Cu₃O_7-δへの元素置換効果
Mar. 2000, 日本物理学会講演概要集第３分冊, 473

Electronic Structure of Ladders and Chains in Sr14-xCaxCu24O41 Studied by X-ray Absorption and Emission Spectroscopies,6th International Conference Materials and Mechanisms of Superconductivity and High Temperature Superconductors
Feb. 2000, Abstract of M2SHTSC-VI,（M2SHTSC-VI, Houston, Texas USA）, 108

Polarization Analysis of X-ray Absorption Spectra in PrBa₂Cu₄O₈ Single Crystal: Hole State Near O-1s Absorption Edge
Feb. 2000, 6^th Internatonal Conference of Materials and Mechanisms of Superconductivity and High Temperature Superconductors, Abstract,（Houston, Texas）, 403

Influence of Pr on electronic structure of plane oxygen in PrBa₂Cu₃O₇ structure by soft X-ray emission spectroscopy
Feb. 2000, ibid., 402

Electronic Structure of Ladders and Chains in Sr14-xCaxCu24O41 Studied by X-ray Absorption and Emission Spectroscopies,6th International Conference Materials and Mechanisms of Superconductivity and High Temperature Superconductors
Feb. 2000, Abstract of M2SHTSC-VI,（M2SHTSC-VI, Houston, Texas USA）, 108

Polarization Analysis of X-ray Absorption Spectra in PrBa₂Cu₄O₈ Single Crystal: Hole State Near O-1s Absorption Edge
Feb. 2000, 6^th Internatonal Conference of Materials and Mechanisms of Superconductivity and High Temperature Superconductors, Abstract,（Houston, Texas）, 403

Influence of Pr on electronic structure of plane oxygen in PrBa₂Cu₃O₇ structure by soft X-ray emission spectroscopy
Feb. 2000, ibid., 402

Resonance photoemission of LaCoO3(111) and La0.9Sr0.1CoO3(111)
THOMAS A G; DUNWOODY P M; GRICE S C; MARR P G D; TEEHAN D; SEDDON E A; ASAI K; KOBOYASHI Y; YAMADA N
2000, J. Phys.: Condens. Matter., 12, 44, 9259-9279, 0953-8984, 80011963687

Sr14-xCaxCu24O41のO1s吸収及び発光分光によるchain，leg，rung位置の酸素の局所電子状態
2000, 日本物理学会2000年春の分科会（関西大学）講演概要集第3分冊, 477

Resonance photoemission of LaCoO3(111) and La0.9Sr0.1CoO3(111)
2000, J. Phys.: Condens. Matter., 12, 44, 9259-9279, 0953-8984, 80011963687

"Electric Structure and Surface Reactivity of La_1-xSr_xCoO₃"
Sep. 1999, Faraday Disscussion 114 - Surface Science of Metal Oxides, Ambleside, UK

PrBa₂Cu₄O₈の酸素吸収端近傍のX線吸収スペクトル
Sep. 1999, 日本物理学会1999年秋の分科会（岩手大学）講演概要集第3分冊, 456

Study of YBa₂Cu₃O_7-δ Ceramics/Al Interface
Sep. 1999, First Vacuum and Surface Science Conference of Asia and Australia, Abstract,（Tokyo）, 54

"Electric Structure and Surface Reactivity of La_1-xSr_xCoO₃"
Sep. 1999, Faraday Disscussion 114 - Surface Science of Metal Oxides, Ambleside, UK

Study of YBa₂Cu₃O_7-δ Ceramics/Al Interface
Sep. 1999, First Vacuum and Surface Science Conference of Asia and Australia, Abstract,（Tokyo）, 54

(Sr1-xCax)14Cu24O41の酸素1s吸収端近傍のX線吸収
Mar. 1999, 日本物理学会第54回年回講演概要集第3分冊, 569

Nuclear spin-spin coupling inLa2−xSrxCuO4studied by stimulated echo decay
S. Fujiyama; M. Takigawa; Y. Ueda; T. Suzuki; N. Yamada
American Physical Society (APS), 1999, Physical Review B, 60, 13, 9801-9809, 0163-1829, 1095-3795, 80011379710

"Hole State in Ladder-compound（Sr,Ca）₁₄Cu₂₄O₄₁ by X-ray Absorption Spectroscopy"
1999, Activity Report of Synchrotron Radiatin Laboratory 1999 ISSP, 88-89

PrBa2Cu2TaO8の電子伝導と電子状態
1999, 第13回日本放射光学会年会・放射光科学合同シンポジウム講演予稿集, 214

YBa2Cu3O7とPrBa2Cu3O7におけるO1sX線吸収端近傍のXAS測定
1999, 第13回日本放射光学会年会・放射光科学合同シンポジウム講演予稿集, 213

PrBa2Cu4O8単結晶の酸素吸収端近傍のホール状態
1999, 第13回日本放射光学会年会・放射光科学合同シンポジウム講演予稿集, 212

（Sr1-xCax）14Cu24O41の酸素1s吸収端近傍のX線吸収
1999, 第13回日本放射光学会年会・放射光科学合同シンポジウム講演予稿集, 116

Zero Bias Anomaly and Preferred Surface Grain Orientation of YBa2Cu3O7-δ Ceramics
1999, Jpn, J. Appl. Phys., 38, 8, 4722-4726, 0021-4922, 110003907487

Nuclear spin-spin coupling in La2-xSrxCuO4 studied by stimulated echo dcay
S. Fujiyama; M. Takigawa; Y. Ueda; T. Suzuki; N. Yamada
American Physical Society (APS), 1999, Physical Review, B, 60, 13, 9801-9809, 0163-1829, 1095-3795, 80011379710

"Hole State in Ladder-compound（Sr,Ca）₁₄Cu₂₄O₄₁ by X-ray Absorption Spectroscopy"
1999, Activity Report of Synchrotron Radiatin Laboratory 1999 ISSP, 88-89

Zero Bias Anomaly and Preferred Surface Grain Orientation of YBa2Cu3O7-δ Ceramics
1999, Jpn, J. Appl. Phys.

酸素位置選別励起によるPrBa2Cu3O7の酸素局所電子状態
Sep. 1998, 日本物理学会1998年秋の分科会講演概要集第３分冊, 705

PrBa₂Cu_2.1Ta_0.9O₈の電気抵抗と電子状態
Sep. 1998, 日本物理学会1998年秋の分科会講演概要集，第３分冊, 648

Synthesis and superconducting properties of (Y1-xPrx) Ba2Cu4O8 and (Y1-xPrx) 2Ba4Cu7O15-y compounds
S. Horii; Y. Yamada; H. Ikuta; N. Yamada; Y. Kodama; S. Katano; Y. Funahashi; S. Morii; A. Matsushita; T. Matsumoto; I. Hirabayashi; U. Mizutani
Both (Y1-xPrx)Ba2Cu4O8 (hereafter abbreviated as Y/Pr124) and (Y1-xPrx)2Ba4Cu7O 15-y, (Y/Pr247) compounds were successfully synthesized over the whole concentration range 0 <
x <
1 by means of either hot isostatic pressing (HIP) technique or high pressure oxygen gas technique. We revealed that the superconducting transition temperature disappears at xc = 0.8 in both systems in contrast to xc = 0.5 for the (Y1-xPrx)Ba2Cu3O7 (Y/Pr123) system reported in the literature and concluded from this that the suppression of superconductivity due to the Pr-doping is weaker in both 124 and 247 systems than that in the 123 system. Furthermore, a combination of the magnetic susceptibility data in the normal state with the Pr-O distance derived from the neutron diffraction experiments led us to conclude that the Pr ion is in the trivalent state for all samples in both 124 and 247 systems. An increase in the critical concentration xc in the Y/Pr124 and Y/Pr247 systems relative to that for the Y/Pr123 system is attributed to an increase in the hybridization of the Pr-4f and O-2p orbitals. © 1998 Elsevier Science B.V. All rights reserved., Elsevier, 10 Jun. 1998, Physica C: Superconductivity and its Applications, 302, 1, 10-22, English, 0921-4534, 0032094759

Synthesis and superconducting properties of (Y1-xPrx) Ba2Cu4O8 and (Y1-xPrx) 2Ba4Cu7O15-y compounds
S. Horii; Y. Yamada; H. Ikuta; N. Yamada; Y. Kodama; S. Katano; Y. Funahashi; S. Morii; A. Matsushita; T. Matsumoto; I. Hirabayashi; U. Mizutani
Both (Y1-xPrx)Ba2Cu4O8 (hereafter abbreviated as Y/Pr124) and (Y1-xPrx)2Ba4Cu7O 15-y, (Y/Pr247) compounds were successfully synthesized over the whole concentration range 0 <
x <
1 by means of either hot isostatic pressing (HIP) technique or high pressure oxygen gas technique. We revealed that the superconducting transition temperature disappears at xc = 0.8 in both systems in contrast to xc = 0.5 for the (Y1-xPrx)Ba2Cu3O7 (Y/Pr123) system reported in the literature and concluded from this that the suppression of superconductivity due to the Pr-doping is weaker in both 124 and 247 systems than that in the 123 system. Furthermore, a combination of the magnetic susceptibility data in the normal state with the Pr-O distance derived from the neutron diffraction experiments led us to conclude that the Pr ion is in the trivalent state for all samples in both 124 and 247 systems. An increase in the critical concentration xc in the Y/Pr124 and Y/Pr247 systems relative to that for the Y/Pr123 system is attributed to an increase in the hybridization of the Pr-4f and O-2p orbitals. © 1998 Elsevier Science B.V. All rights reserved., Elsevier, 10 Jun. 1998, Physica C: Superconductivity and its Applications, 302, 1, 10-22, English, 0921-4534, 0032094759

MUON SPIN RELAXATION STUDY ON MADNETIC ORDERING IN PDBa2Cu4O8
1996, HYPERFINE INTERACTIONS(C), 1, 183

MUON SPIN RELAXATION STUDY ON MADNETIC ORDERING IN PDBa2Cu4O8
1996, HYPERFINE INTERACTIONS(C), 1, 183

MECHANISM OF SUPPRESSION OF SUPERCONDUCTIVITY IN (PRXY1-X)BA2CU4O8
N YAMADA; Z GUO; H YAMAZAKI; H NISHIKAWA; T IRI; KI GONDAIRA; K KOHN
The effect of Pr on the superconductivity in (PrxY1-x)Ba2Cu4O8 were studied and compared with that in (PrxY1-x)Ba2Cu3O7. Transition temperatures of the (PrxY1-x)Ba2Cu4O8 compounds decrease with increasing Pr content x, although the rate of decrease is slower than that of (PrxY1-x)Ba2Cu3O7. Thus the Pr has a weaker effect to the superconductivity suppression in (PrxY1-x)Ba2Cu4O8 than in (PrxY1-x)Ba2Cu3O7. From the analysis of X-ray absorption spectra(XAS) near O K-edge in (PrxY1-x)Ba2Cu4O8 and in (PrxY1-x)Ba2Cu3O7, the effect of Pr substitution on the O 2p electronic state is found to be weaker for (PrxY1-x)Ba2Cu4O8, which is parallel to the effect on superconductivity. These results were well explained with the hole localization model based on the hybridization of Pr 4f and O 2p orbitals., ELSEVIER SCIENCE BV, Dec. 1994, PHYSICA C, 235, Pt 2, 1029-1030, English, 0921-4534, WOS:A1994QC69400154

MECHANISM OF SUPPRESSION OF SUPERCONDUCTIVITY IN (PRXY1-X)BA2CU4O8
N YAMADA; Z GUO; H YAMAZAKI; H NISHIKAWA; T IRI; KI GONDAIRA; K KOHN
The effect of Pr on the superconductivity in (PrxY1-x)Ba2Cu4O8 were studied and compared with that in (PrxY1-x)Ba2Cu3O7. Transition temperatures of the (PrxY1-x)Ba2Cu4O8 compounds decrease with increasing Pr content x, although the rate of decrease is slower than that of (PrxY1-x)Ba2Cu3O7. Thus the Pr has a weaker effect to the superconductivity suppression in (PrxY1-x)Ba2Cu4O8 than in (PrxY1-x)Ba2Cu3O7. From the analysis of X-ray absorption spectra(XAS) near O K-edge in (PrxY1-x)Ba2Cu4O8 and in (PrxY1-x)Ba2Cu3O7, the effect of Pr substitution on the O 2p electronic state is found to be weaker for (PrxY1-x)Ba2Cu4O8, which is parallel to the effect on superconductivity. These results were well explained with the hole localization model based on the hybridization of Pr 4f and O 2p orbitals., ELSEVIER SCIENCE BV, Dec. 1994, PHYSICA C, 235, Pt 2, 1029-1030, English, 0921-4534, WOS:A1994QC69400154

SUPERCONDUCTING PROPERTIES OF (Y1-XPRX)BA2CU4O8 COMPOUNDS
Z GUO; N YAMADA; KI GONDAIRA; T IRI; K KOHN
(Y1-xPTx)Ba2Cu4O8 compounds with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were synthesized using a high-pressure oxygen technique. The solubility limit x(s) in this compound system was found to be 0.7. In this composition range, (Y1-xPrx)Ba2Cu4O8 compounds have the YBa2Cu4O8(124) structure and the lattice parameters a, b and c increase with increasing Pr content x. The superconducting transition temperature T-c decreases monotonically with increasing x, and the critical content x(c), where superconductivity disappears, has been estimated to be 0.8. There is an obvious effect of Pr substitution on superconductivity, although the effect is smaller in the 124 system than that in the 123 system. X-ray diffraction results suggest that Pr is almost 3+ in this system. A model for the Pr substitution is suggested to make holes immobile to suppress superconductivity as the result of the hybridization of O 2p(x) with Pr 4f orbitals., ELSEVIER SCIENCE BV, Feb. 1994, PHYSICA C, 220, 1-2, 41-49, English, 0921-4534, 80007451003, WOS:A1994MW36800005

SUPERCONDUCTING PROPERTIES OF (Y1-XPRX)BA2CU4O8 COMPOUNDS
Z GUO; N YAMADA; KI GONDAIRA; T IRI; K KOHN
(Y1-xPTx)Ba2Cu4O8 compounds with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were synthesized using a high-pressure oxygen technique. The solubility limit x(s) in this compound system was found to be 0.7. In this composition range, (Y1-xPrx)Ba2Cu4O8 compounds have the YBa2Cu4O8(124) structure and the lattice parameters a, b and c increase with increasing Pr content x. The superconducting transition temperature T-c decreases monotonically with increasing x, and the critical content x(c), where superconductivity disappears, has been estimated to be 0.8. There is an obvious effect of Pr substitution on superconductivity, although the effect is smaller in the 124 system than that in the 123 system. X-ray diffraction results suggest that Pr is almost 3+ in this system. A model for the Pr substitution is suggested to make holes immobile to suppress superconductivity as the result of the hybridization of O 2p(x) with Pr 4f orbitals., ELSEVIER SCIENCE BV, Feb. 1994, PHYSICA C, 220, 1-2, 41-49, English, 0921-4534, 80007451003, WOS:A1994MW36800005

VALENCE STATES OF PRASEODYMIUM IN Y-BA-CU OXIDES STUDIED BY X-RAY-PHOTOELECTRON SPECTROSCOPY
M NAGOSHI; Y FUKUDA; N YAMADA; Z GUO; T IRI; K GONDAIRA; H IWASAKI; Y SYONO; M TACHIKI
Pr 3d and 4d core levels have been studied for Y0.4Pr0.6Ba2Cu4O8 and PrBa2Cu3O7 using x-ray-photoelectron spectroscopy to elucidate the valence states. The features of Pr 3d and 4d are close to those for Pr2O3 for both compounds, while they are different from those for Pr6O11. It is concluded that praseodymium is almost trivalent with a 4f2 configuration., AMERICAN PHYSICAL SOC, Oct. 1992, PHYSICAL REVIEW B, 46, 13, 8635-8637, English, Introduction scientific journal, 0163-1829, 80006733408, 10002640, WOS:A1992JT04000090

XPSによるY-Ba-Cu酸化物におけるPrの価数状態
1992, Physical Review B, 46, 8635

Effect of Pr Substitution on Superconductivity in (PrxY1-x)Ba2Cu4O8
1991, Physica C, 185-189

Effect of Pr Substitution on Superconductivity in (PrxY1-x)Ba2Cu4O8
1991, Physica C, 185-189

Atomic Magnetic Moment and Exchange Interaction between Mn Atoms in Intermetallic Compounds in Mn-Ge System
1990, Journal of Physical Society of Japan, 59, 1

Atomic Magnetic Moment and Exchange Interaction between Mn Atoms in Intermetallic Compounds in Mn-Ge System
1990, Journal of Physical Society of Japan, 59, 1

Magnetic Properties of ε-Mn3Ge
1988, Physica B, 149

Magnetic Properties of ζ1-Mn2.6Ge
1988, Journal de Physique, C8, 49

Magnetic Properties of ε-Mn3Ge
1988, Physica B, 149

Magnetic Properties of ζ1-Mn2.6Ge
1988, Journal de Physique, C8, 49

Magnetic Structure of Intermetallic Compound K-Mn5Ge2
1987, Journal of Physical Society of Japan, 56, 11

Magnetic Structure of Intermetallic Compound K-Mn5Ge2
1987, Journal of Physical Society of Japan, 56, 11

Magnetic Properties of Intermetallic Compound Mn11Ge8
1986, Journal of Physical Society of Japan, 55, 11

Magnetic Properties of Intermetallic Compound Mn11Ge8
1986, Journal of Physical Society of Japan, 55, 11

遷移金属金属間化合物の磁気モーメントと交換積分に与える環境効果の研究

YBa2Cu4O8へのPr置換の超伝導に対する効果の研究

超伝導２硼化物の電子状態の研究

Study on the effect of local environment on the magnetic moment and exchange interaction in transition intermetallic compound.

Study on the effect of Pr Substitution on Super conductivity in YBa2Cu408

Study on electronic state in superconducting diboride