2002 Fiscal Year Annual Research Report

銅酸化物高温超伝導体の磁気励起

Research Project

Project/Area Number	14038223
Research Institution	Nagoya University
Principal Investigator	佐藤正俊名古屋大学, 大学院・理学研究科, 教授 (40092225)
Keywords	銅酸化物 / 中性子散乱 / 磁気励起 / フォノン / ストライプ / Cu-NQR
Research Abstract	銅酸化物高温超伝導体および他の関連物質系の物性を研究した。特に銅酸化物の高温超伝導発現機構が磁気的相互作用によるとする立場から残った問題に取り組んだ。La214系では"ストライプ"と呼ばれる1次元的電荷秩序が正孔濃度p〜1/8に現れ種々の物理量に影響を与え、さらには超伝導を抑制する(いわゆる1/8異常)。逆に動的な"ストライプ"はその空間的非一様性を通して超伝導電子対の形成を促進するのではないかとの考えも提案された。この考えの正否を探るには、超伝導電子対形成に影響を及ぼすほどゆっくりした"ストライプ"ゆらぎが、La214系以外の高温超伝導体にも存在するかどうかを知らねばならない。このことに関して、YBa_2Cu_3O_y(Y123)系やNd_<1.6-x>Ce_xSr_<0.4>CuO_<4-δ> (T^)系、さらにはLa214系のひとつで静的"ストライプ"秩序を持つLa_<1.6>Nd_<0.4>Sr_xCuO4_4(x=0.12)を取り上げ、その磁気励起スペクトルやフォノンの中性子散乱による研究、種々の手段による1/8異常の有無に関する研究等を行った。その結果、Y123系の磁気励起スペクトルにおいて、動的"ストライプ"の存在を示すといわれたその特徴が、"ストライプ"を考慮しないモデルでよく説明されることがわかった。動的"ストライプ"が存在する場合にその効果が見られるはずのフォノンにもなんら効果が見られない。T^系のCu-NQR信号のwipeout現象にも他の物理量にも1/8異常が全く見られず、動的"ストライプ"がどの系にも共通に存在し超伝導発現に関わっているという可能性はかなり小さくなった。"ストライプ"はLa214系の構造上の特徴に深く結びついて現れるようだが、現在、La_<1.6>Nd_<0.4>Sr_xCuO_4(x=0.12)を用いて構造との関係を詳しく調べているところである。

Research Products

(22 results)

All Other

All Publications (22 results)

[Publications] N.Aito: "Spin-Glass-Like Transition and Hall Resistivity of Y_<2-x>Bi_xIr_2O_7"J.Phys.Soc.Jpn.. 72 NO.5(in press). (2003)
[Publications] H.Masuda: "Transport and Magnetic Properties of R_<1-x>A_xCoO_3 (R=La, Pr and Nd ; A=Ba, Sr and Ca)"J.Phys.Soc.Jpn.. 72 NO.4(in press). (2003)
[Publications] Y.Yasui: "Neutron Scattering Studies of Pyrochlore Compound Nd_2Mo_2O_7 in Magnetic Field"J.Phys.Soc.Jpn.. 72 NO.4(in press). (2003)
[Publications] T.Ido: "Anomalous Hall Effect and Magnetoresistance of SrFe_<1-x>Co_xO_<3+δ>"J.Phys.Soc.Jpn.. 72 NO.2. 357-363 (2003)
[Publications] T.Miyashita: "^<59>Co-NMR Studies on La_4Co_3O_<10+δ>"J.Phys.Soc.Jpn.. 71 NO.12. 3043-3046 (2002)
[Publications] S.Iikubo: "Magnetic Structure and the Hall Resistivity of Cu_<1-x>Zn_xCr_2Se_4"J.Phys.Soc.Jpn.. 71 NO.11. 2792-2799 (2002)
[Publications] 安井幸夫: "スピンアイス系の磁気相関"日本物理学会誌. 57 NO.11. 830-834 (2002)
[Publications] Y.Yoshi: "Specific Heat Study in Pyrochlore Molybdates Nd_<2-x>Y_xMo_2O_7"J.Phys.Soc.Jpn.. 71 NO.3. 997-998 (2002)
[Publications] Y.Yasui: "Static Correlation and Dynamical Properties of Tb^<3+>-moments in Tb_2Ti_2O_7 -Neutron Scattering Study-"J.Phys.Soc.Jpn.. 71 NO.2. 599-606 (2002)
[Publications] M.Ambai: "Transport and NQR Studies of Nd_<1.6-x>Ce_xSr_<0.4>CuO_<4-δ> with T^* Structure"J.Phys.Soc.Jpn.. 71 NO.2. 538-542 (2002)
[Publications] M.Kanada: "Neutron Scattering Study of the Spin Correlation in the Spin Ice System Ho_2Ti_2O_7"J.Phys.Soc.Jpn.. 71 NO.1. 313-318 (2002)
[Publications] M.Sato: "Comparative Study on the Magnetic Excitation Spectra of Y123 and La214 High-T_c Systems -Are the Dynamical Stripes Important?-"Physica B. (in press). (2003)
[Publications] S.Iikubo: "Magnetic Structure and the Anomalous Hall Effect of Cu_<1-x>Zn_xCr_2Se_4"Physica B. (in press). (2003)
[Publications] Y.Yasui: "Detailed Studies on the Anomalous Hall Effect of Pyrochlore Molybdates"Physica B. (in press). (2003)
[Publications] M.Ito: "Neutron Scattering Studies on In-Plane Longitudinal Phonons of YBa_2Cu_3O_y"Physica C. (in press). (2003)
[Publications] T.Ido: "Anomalous Hall Effect and Magnetoresistance of SrFe_<1-x>Co_xO_<3+δ>"Physica B. (in press). (2003)
[Publications] Y.Kobayashi: "NMR studies of Co-Oxides with Large Thermoelectric Performance"Physica B. (in press). (2003)
[Publications] Y.Fudamoto: "μSR Studies of Two-Dimensional Antiferromagnets CaV_3O_7 and SrV_3O_7"Physica B. (in press). (2003)
[Publications] M.Soda: "Transport, Thermal and Magnetic Properties of Pyrochlore Oxides Y_<2-x>Bi_xIr_2O_7"Physica B. (in press). (2003)
[Publications] T.Fujita: "Transport, Thermal and Magnetic Properties of Bi_3Os_3O_<11> and Bi_3Ru_3O_<11>"Physics B. (in press). (2003)
[Publications] T.Miyashita: "Spin-State Change of Co Atoms of La_4Co_3O_<10+δ>"Physica B. (in press). (2003)
[Publications] J.Okamoto: "Electronic Structure of the Pyrochlore-type Ru-Oxides through the Metal-Semiconductor Transition"Acta Physica Polonica B. (in press). (2003)

2002 Fiscal Year Annual Research Report

銅酸化物高温超伝導体の磁気励起

Principal Investigator

佐藤 正俊 名古屋大学, 大学院・理学研究科, 教授 (40092225)

Research Products

[Publications] N.Aito: "Spin-Glass-Like Transition and Hall Resistivity of Y_<2-x>Bi_xIr_2O_7"J.Phys.Soc.Jpn.. 72 NO.5(in press). (2003)

[Publications] H.Masuda: "Transport and Magnetic Properties of R_<1-x>A_xCoO_3 (R=La, Pr and Nd ; A=Ba, Sr and Ca)"J.Phys.Soc.Jpn.. 72 NO.4(in press). (2003)

[Publications] Y.Yasui: "Neutron Scattering Studies of Pyrochlore Compound Nd_2Mo_2O_7 in Magnetic Field"J.Phys.Soc.Jpn.. 72 NO.4(in press). (2003)

[Publications] T.Ido: "Anomalous Hall Effect and Magnetoresistance of SrFe_<1-x>Co_xO_<3+δ>"J.Phys.Soc.Jpn.. 72 NO.2. 357-363 (2003)

[Publications] T.Miyashita: "^<59>Co-NMR Studies on La_4Co_3O_<10+δ>"J.Phys.Soc.Jpn.. 71 NO.12. 3043-3046 (2002)

[Publications] S.Iikubo: "Magnetic Structure and the Hall Resistivity of Cu_<1-x>Zn_xCr_2Se_4"J.Phys.Soc.Jpn.. 71 NO.11. 2792-2799 (2002)

[Publications] 安井 幸夫: "スピンアイス系の磁気相関"日本物理学会誌. 57 NO.11. 830-834 (2002)

[Publications] Y.Yoshi: "Specific Heat Study in Pyrochlore Molybdates Nd_<2-x>Y_xMo_2O_7"J.Phys.Soc.Jpn.. 71 NO.3. 997-998 (2002)

[Publications] Y.Yasui: "Static Correlation and Dynamical Properties of Tb^<3+>-moments in Tb_2Ti_2O_7 -Neutron Scattering Study-"J.Phys.Soc.Jpn.. 71 NO.2. 599-606 (2002)

[Publications] M.Ambai: "Transport and NQR Studies of Nd_<1.6-x>Ce_xSr_<0.4>CuO_<4-δ> with T^* Structure"J.Phys.Soc.Jpn.. 71 NO.2. 538-542 (2002)

[Publications] M.Kanada: "Neutron Scattering Study of the Spin Correlation in the Spin Ice System Ho_2Ti_2O_7"J.Phys.Soc.Jpn.. 71 NO.1. 313-318 (2002)

[Publications] M.Sato: "Comparative Study on the Magnetic Excitation Spectra of Y123 and La214 High-T_c Systems -Are the Dynamical Stripes Important?-"Physica B. (in press). (2003)

[Publications] S.Iikubo: "Magnetic Structure and the Anomalous Hall Effect of Cu_<1-x>Zn_xCr_2Se_4"Physica B. (in press). (2003)

[Publications] Y.Yasui: "Detailed Studies on the Anomalous Hall Effect of Pyrochlore Molybdates"Physica B. (in press). (2003)

[Publications] M.Ito: "Neutron Scattering Studies on In-Plane Longitudinal Phonons of YBa_2Cu_3O_y"Physica C. (in press). (2003)

[Publications] T.Ido: "Anomalous Hall Effect and Magnetoresistance of SrFe_<1-x>Co_xO_<3+δ>"Physica B. (in press). (2003)

[Publications] Y.Kobayashi: "NMR studies of Co-Oxides with Large Thermoelectric Performance"Physica B. (in press). (2003)

[Publications] Y.Fudamoto: "μSR Studies of Two-Dimensional Antiferromagnets CaV_3O_7 and SrV_3O_7"Physica B. (in press). (2003)

[Publications] M.Soda: "Transport, Thermal and Magnetic Properties of Pyrochlore Oxides Y_<2-x>Bi_xIr_2O_7"Physica B. (in press). (2003)

[Publications] T.Fujita: "Transport, Thermal and Magnetic Properties of Bi_3Os_3O_<11> and Bi_3Ru_3O_<11>"Physics B. (in press). (2003)

[Publications] T.Miyashita: "Spin-State Change of Co Atoms of La_4Co_3O_<10+δ>"Physica B. (in press). (2003)

[Publications] J.Okamoto: "Electronic Structure of the Pyrochlore-type Ru-Oxides through the Metal-Semiconductor Transition"Acta Physica Polonica B. (in press). (2003)

佐藤正俊名古屋大学, 大学院・理学研究科, 教授 (40092225)

[Publications] 安井幸夫: "スピンアイス系の磁気相関"日本物理学会誌. 57 NO.11. 830-834 (2002)