論文 - 的場　正憲

Photoemission Study of the Electronic Structure of the Ferromagnetic Cr_1-δTe System

Kenya Shimada, Tomohiko Saitoh, Hirofumi Namatame, Atsushi Fujimori, Masanori Matoba, Kazuo Hatakeyama and Shuichiro Anzai

Activity Report of Syncrotron Radiation Laboratory 1993   46-47 1993年

研究論文（その他学術会議資料等）, 共著

Co Substitution Effect on the Electronic Structure of NiS Studied by X-Ray Photoemission Spectroscopy

Takeshi Mamori, Masanori Matoba, Atsushi Fujimori and Shuichiro Anzai

Journal of the Physical Society of Japan 61   433-436 1992年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

X-ray photoemission spectroscopy (XPS) measurements of the valence band, Ni 2p core level, Co 2p core level and S 2s, 2p core levels were carried out on the metallic state of Ni1-vCovS (0≤ v≤ 0.06). The main peak of the valence band spectra shifts toward lower binding energy (E B) with increasing v ( dE B/ dv=-2.6± 0.4 eV/mol). This behavior is different from those reported on vacancy introduction or on the Se substitution in Ni1-xS or NiS1-y Sey ( dE B/ dxapprox 0; dE B/ dyapprox 0). The Ni 2p3/2 core level peak also shifts toward lower E B ( dE B/ dv=-1.8± 0.6 eV/mol), while no change in the S 2s or 2p core level peak is observed. We propose the possibility that the hybridization between the Co d7L and the Ni d8L peaks near the E F, where L denotes a ligand hole, leads to the modification of the electronic state of Ni sites in Ni1-vCovS.

Thermal Expansion Behaviours through the Charge-Transfer Type Nonmetal-Metal Transition in Ni_1-rM_rS (M=Ti, V and Cr)

Masanori Matoba, Shuichiro Anzai and Mitsuya Uchida

Journal of the Physical Society of Japan 61   1425-1426 1992年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Thermal Expansion, Thermoelectric Power, and XPS Study of the Nonmeta-Metal Transition in Ni_1-xS_1-ySe_y

Masanori Matoba, Shuichiro Anzai and Atsushi Fujimori

Journal of the Physical Society of Japan 60   4230-4244 1991年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

　概要を見る

Magnetic susceptibility χ, electrical resistivity ρ, thermoelectric power S, XPS spectra and hexagonal lattice parameters c and a are measured on the NiAs-type Ni_1-x_S_1-y_Se_y_ (x≤0.04; y≤1.00). We find the followings (1) the nonmetal-metal transition temperature T_t_, the phonon-drag coefficient C below T_t_ and dχ(T>T_t_)/dT decrease and they are suppressed at x_c_ and y_c_ with increase in x and y, respectively. (2) The nearest neighboring S_1-y_Se_y_(Z)-Z, Ni-Z and Ni-Ni distances just below T_t_ (D_Z-Z_N, D_Ni-Z_N, D_Ni-Ni_N, respectively) are depressed with increase in x. D_Z-Z_N and D_Ni-Ni_N only slightly depend on y, while D_Ni-Z_N increases with increasing y. (3) No change in the d8L peak (L: hole in the Z network) in the valence band region is observed among Ni_1-x_S_1-y_Se_y_ and Ni_0.93_Te. (4) The Ni 2p_3/2_d^9^L core level peak shifts to lower binding energy E_B_ with increasing y, while it hardly changes with x. (5) The E_B_ of S 2s and S 2p core levels decrease with increasing textotx; the EB of S 2p one decreases with increasing y. From the view point of the charge-transfer model, the pressure and the Ni-vacancy substitution effects on Tt are mainly explained by the increase in the Z(p) band width, and the Se-substitution effect by the decrease in the charge-transfer energy. The Ni-vacancies also introduce extra holes in the Z(p) band.

Photoemission study of the metal-nonmetal transition in NiS

Atsushi Fujimori, Hirofumi Namatame, Masanori Matoba and Shuichiro Anzai

Physical Review B 42   620-623 1990年07月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

We have observed small changes in the ultraviolet photoemission spectra of NiS across the temperature-induced phase transition between the Pauli-paramagnetic metal and the antiferromagnetic nonmetal. In going from the nonmetallic to the metallic phases, the main band (d8L) within ~3 eV below the Fermi level EF is shifted toward EF by 0.05 eV. This observation is consistent with the closing of a S 3p–Ni 3d charge-transfer gap and cannot be reconciled with that of a band gap of antiferromagnetic origin. The spectrum loses a small fraction of intensity in the vicinity of EF as the gap is collapsed. The virtually identical line shape of the main band between the two phases is consistent with the persistence of short-range antiferromagnetic correlation in the paramagnetic phase.

Conductivity Phase Transition with Shift of Valence-Band Edge and with Structural Distortion in Cu₄Sn_1-xGe_xS₄

Takayuki Kamimura, Masanori Matoba and Shuichiro Anzai

Journal of the Physical Society of Japan 59   3045-3048 1990年06月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

X-ray diffraction, electrical resistivity, DSC and XPS investigations were carried out on Cu4Sn1-xGexS4 (0≤x≤1.0). At room temperature, the orthorhombic structure changes to a monoclinic one at a transition concentration of xt=0.6 as x increases. This transition also exhibits the expansions in the energy width between the top of the valence band and the Fermi level and in the lattice parameter B. The transition has the characteristics of the first-order high (high temperature)-to-low (low temperature) conductivity phase transition as reported on Cu4SnS4. The transition temperature Tt linearly increases with x. These features are briefly compared with the electronic and structural phase transition reported on SnTe and Pb1-xGexTe.

高電導性半導体Cu₄SnS₄の電導度相転移に対する不純物置換の物性制御効果

安西 修一郎, 井上 郁也, 的場 正憲, 上村 隆之

旭硝子財団研究報告 57   229-239 1990年

研究論文（その他学術会議資料等）, 共著

Conductivity Phase Transition in Cu₄Sn(S_1-ySe_y)₄

Shuichiro Anzai, Masanori Matoba, Ikuya Inoue, Tadahiro Fukazawa, Takayuki Kamimura and Kazuhiko Kitamura

Journal of the Physical Society of Japan 59   3799-3800 1990年

研究論文（学術雑誌）, 共著, 査読有り

Cu₄SnS₄の熱電能

的場 正憲, 井上 郁也, 上村 隆之, 渡辺 守生, 安西 修一郎

日本材料科学会誌 27   299-301 1990年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

　概要を見る

Cu_4_SnS_4_の電導度相転移温度に熱電能の異常を見い出した。また, 本物質の熱電性能指数Zは約8×10^-4^K^-1^とかなり大きいことがわかった。

Electron correlation and magnetism in NiS: Implications of photoemission spectra

Atsushi Fujimori, Kiyoyuki Terakura, Masaki Taniguchi, Susumu Ogawa, Shigemasa Suga, Masanori Matoba and Shuichiro Anzai

Physical Review B 37   3109-3112 1988年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

The photoemission spectra of NiS in both antiferromagnetic and Pauli paramagnetic phases show similar characteristic features of localized d electrons. This finding is in contrast with the results of band-structure calculations which predict drastic spectral changes between the two phases. It is suggested that fluctuations of the Ni 3d local moments due to hybridization with S 3p states near the Fermi level are responsible for the Pauli paramagnetic behavior.

熱電能(室温以下)の測定法と高温超伝導体YBa₂Cu₃O_7-xへの応用

的場 正憲, 安西 修一郎, 王子 雅章

日本材料科学会誌 25   173-176 1988年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

　概要を見る

熱起電力のゼロレベルをはっきりさせることを念頭においた低温での熱起電力の温度変化測定法を開発した。これを用いて，超伝導状態にある酸化物高温超伝導化合物の熱起電力ゼロを示した。

Electron correlation and magnetism in NiS: Implications of photoemission spectra

Atsushi Fujimori, Kiyoyuki Terakura, Masaki Taniguchi, Susumu Ogawa, Shigemasa Suga, Masanori Matoba and Shuichiro Anzai

Technical Report of the Institute for Solid State Physics 1987   1-14 1987年

研究論文（その他学術会議資料等）, 共著

　概要を見る

We have performed the photoemission spectroscopic study of NiS in both antiferromagnetic and Pauli paramagnetic phases below and above T_t_. The spectra show similar characteristic features of localized d electrons. It is suggested that fluctuations of the Ni 3d local moments due to hybridization with S 3p states near the Fermi level are responsible for the Pauli paramagnetic behavior above T_t_.

The T²-Contribution to the Electrical Resistivity at Low Temperatures in NiAs-type Ni_1-xS_1-ySe_y

Masanori Matoba and Shuichiro Anzai

Journal of Magnetism and Magnetic Materials 70   213-214 1987年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

　概要を見る

The y(1-y)-like maxima in Ni0.98S1-ySey are found beyond yc in the y-dependences of the coefficient of the T2 contribution to the resistivity and of the residual resistivity. Here, the critical concentration of the antiferromagnetic and less-conductive phase is determined to be yc = 0.095.

Localized versus Itinerant Character of d Electrons in NiS: Photoemission Spectroscopic Study

Atsushi Fujimori, Masanori Matoba, Shuichiro Anzai, Kiyoyuki Terakura, Masaki Taniguchi, Susumu Ogawa and Shigemasa Suga

Journal of Magnetism and Magnetic Materials 70   67-69 1987年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

The electronic structure of NiS on both sides of the metal-nonmetal transition has been studied by photoemission spectroscopy using synchrotron radiation and compared with band structure calculations. Interplay between Ni d-ligand hybridization, electron correlation, exchange interaction, and d-band formation is discussed.

Photoemission Study of the Electronic Structure and the Metal-nonmetal Transition in NiS

Atsushi Fujimori, Masanori Matoba, Shuichiro Anzai, Masaki Taniguchi, Susumu Ogawa, and Shigemasa Suga

Activity Report of Synchrotron Radiation Laboratory 1986   51-52 1986年

研究論文（その他学術会議資料等）, 共著

　概要を見る

The photoemission spectra of NiS, wchich exhits an antiferromagnetic nonmetal-to-a Pauli paramagnetic metal at T_t_=263K, have been measured. The spectra show similar characteristic features of localized d electrons, in contrast with the results of band-structure calculations which predict drastic spectral changes between the two phases.

Effect of Se-Substitution on the Magnetic and Electrical Transition in the NiAs-type NiS

Shuichiro Anzai, Masanori Matoba, Masakazu Hatori and Hiroshi Sakamoto

Journal of the Physical Society of Japan 55   2531-2534 1986年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

Hexagonal lattice parameters a and c of the NiAs-type NiS_1-y_Se_y_ expand with increasing y below the solubility limit y_L_=0.20. The first-order transition temperature T_t_(y) [between the antiferromagnetic less-conductive and the Pauli-paramagnetichigh-conductive states] decreases with increasing y, and is suppressed down to 4.2K at the critical concentration y_c_=0.l33. Just above T_t_, the temperature slope of the susceptibility has positive sign at low y, and shows a y-dependence. The isothermal susceptibility of the Pauli-paramagnetic state decreases with increasing y. These experimental results are discussed on the basis of the strongly correlated features of d and p bands in NiS.