2003 Fiscal Year Annual Research Report

常温でハーフメタル状態を発現する層状酸化物の創製

Research Project

Project/Area Number	15206002
Research Category	Grant-in-Aid for Scientific Research (A)
Research Institution	Tokyo Institute of Technology
Principal Investigator	山内尚雄東京工業大学, 応用セラミックス研究所, 教授 (50271581)
Co-Investigator(Kenkyū-buntansha)	本橋輝樹東京工業大学, 応用セラミックス研究所, 助手 (00323840) KARPPINEN Maarit 東京工業大学, 応用セラミックス研究所, 助教授 (50334529) 浜田典昭東京理科大学, 理工学部, 教授 (00126145)
Keywords	ハーフメタル / スピンエレクトロニクス / 層状遷移金属酸化物 / ダブルペロブスカイト / 混合原子価状態 / メスバウアー分光 / FLAPW法バンド計算
Research Abstract	本研究では、層状ダプルペロブスカイト酸化物A(RE)B_2O_<5+δ>(A, RE, Bはそれぞれアルカリ土類金属、希土類、遷移金属元素)を中心とした物質群において、(1)組成と原子配列、(2)電子状態、(3)電気/スピン伝導物性を総合的に研究し、100%スピン偏極度を持ちスピンエレクトロニクス応用が期待されているハーフメタル材料を創製することを目的とする。本年度の主な研究成果を以下に列挙する。 1.BaREFe_2O_<5.0>及びBaRECo_2O_<5+δ>試料における電子状態と化学組成/局所結晶構造の相関関係上記2種類の物質について、(1)酸素量制御や元素置換など化学組成制御、(2)〜4GPaの超高圧印加を施した試料の結晶構造及び電磁気特性を調べた。その結果、これら物質の磁気/電荷秩序状態は遷移金属元素の原子価状態や局所結晶構造と深い相関関係があることが分かった。 2.ハーフメタル酸化物A_2FeTO_6(A=Ba, Sr, Ca, T=Mo, Re)におけるメスバウアー分光上記物質におけるハーフメタル電子状態とFeの原子価状態の関係を調べるため、様々な組成を持つ試料についてメスバウアー分光測定を行った。その結果、(1)Feの原子価状態(混合原子価状態)がAサイトの平均イオン半径r(A^<2+>)により変化すること、(2)T=Reではr(A^<2+>)が小さくなるに従いアイソマーシフトIが単調に低下するが、T=MoではBa→Srの範囲で同様な傾向が見られたものの、Sr→Caの範囲ではIの値がほぼ一定となることが分かった。 3.Na_xCoO_2におけるFLAPW法バンド計算優れた熱電特性や異常超伝導発現が報告されているNa_xCoO_2について、FLAPW法によるバンド計算を行った。その結果、(1)超伝導が発現するNa量x=0.35付近の組成でE_F上の状態密度が非常に高くなり得る、(2)Na量xが低下するに従い磁気秩序状態が安定となり、強磁性相ではハーフメタル電子状態が実現する、ことなどが示唆された。

Research Products
(26 results)

All Other

All Publications (26 results)

[Publications] C.A.Cardoso, F.M.Araujo-Moreira, V.P.S.Awana, E.Takayama-Muromachi, O.F.de Lima, H.Yamauchi, M.Karppinen: "Spin glass behavior in RuSr_2Gd_<1.5>Ce_<0.5>Cu_2O_<10-δ>"Physical Review B. 67. R20407-R20410 (2003)
[Publications] T.Motohashi, R.Ueda, E.Naujalis, T.Tojo, I.Terasaki, T.Atake, M.Karppinen, H.Yamauchi: "Unconventional magnetic transition and transport behavior in Na_<0.75>CoO_2"Physical Review B. 67. 64406-64410 (2003)
[Publications] M.Karppinen, K.Kotiranta, T.Nakane, S.C.Chang, J.M.Chen, R.S.Liu, H.Yamauchi: "Layer-specific hole concentrations in Bi_2Sr_2(Y_<1-x>Ca_x)Cu_2O_<8+δ> as probed by XANES spectroscopy and coulometric redox analysis"Physical Review B. 67. 134522-134527 (2003)
[Publications] V.P.S.Awana, E.Takayama-Muromachi, S.K.Malik, W.B.Yelon, M.Karppinen, H.Yamauchi, V.V.Krishnamurthy: "Cation intermixing and ordering phenomenon in M-O layer of MSr_2YCu_2O_2 (M-1212) compounds with M=Fe, Co, Al, and Ga : a neutron powder diffraction study"Journal of Applied Physics. 93. 8221-8223 (2003)
[Publications] Y.Morita, M.Karppinen, H.Yamauchi, R.S.Liu, J.M.Chen: "XANES study on the evolution among different copper species, Cu^I, Cu^<II> and Cu^<III>, in CuBa_2YCu_2O_<6+z> upon Oxygen Loading"Journal of Low Temperature Physics. 131. 381-386 (2003)
[Publications] H.Yamauchi, M.Karppinen: "Relationship between local atomic arrangements and properties of high-T_c superconductive copper oxides"Journal of Low Temperature Physics. 131. 705-717 (2003)
[Publications] V.P.S.Awana, M.Karppinen, H.Yamauchi, M.Matvejeff, R.S.Liu, L.-Y.Jang: "Oxygen content and valence of Ru in RuSr_2(Gd_<0.75>Ce_<0.25>)_2Cu_2O_<10-δ>"Journal of Low Temperature Physics. 131. 1211-1216 (2003)
[Publications] V.P.S.Awana, E.Takayama-Muromachi, M.Karppinen, H.Yamauchi: "Magneto-superconductivity of 100-atm O_2-annealed RuSr_2Gd_<1.5>Ce<0.5>Cu_2O_<10-δ>"Physica C. 390. 233-238 (2003)
[Publications] J.Sugiyama, H.Itahara, J.H.Brewer, E.J.Ansaldo, T.Motohashi, M.Karppinen, H.Yamauchi: "Static magnetic order in Na_<0.75>CoO_2 detected by muon spin rotation and relaxation"Physical Review B. 67. 214420-214424 (2003)
[Publications] M.Karppinen, S.Lee, J.M.Lee, J.Poulsen, T.Nomura, S.Tajima, J.M.Chen, R.S.Liu, H.Yamauchi: "Hole doping in Pb-free and Pb-substituted (Bi, Pb)_2Sr_2Ca_2Cu_3O<10+δ> superconductors"Physical Review B. 68. 54502-54506 (2003)
[Publications] T.Motohashi, R.Ueda, E.Naujalis, T.Tojo, I.Terasaki, T.Atake, M.Karppinen, H.Yamauchi: "Unconventional electronic transition in Na_xCoO_2 with a precisely controlled Na nonstoichiometry"Physica B. 329-333. 914-915 (2003)
[Publications] Y.Morita, H.Yamauchi, M.Karppinen: "Superconductivity in CoSr_2(Y_<1-x>Ca_x)Cu_2O_<7+δ>"Solid State Communications. 127. 493-498 (2003)
[Publications] Y.Moritomo, M.Hanawa, Y.Ohishi, K.Kato, J.Nakamura, M.Karppinen, H.Yamauchi: "Physical pressure effect on the charge-ordering transition of BaSmFe_2O_<5.0>"Physical Review B. 68. R60101-R60104 (2003)
[Publications] M.Karppinen, V.P.S.Awana, Y.Morita, H.Yamauchi: "Oxygen stoichiometry in Co-1212, Co-1222 and Co-1232 of the homologous series Co-12s2 of "category-B" layered copper oxides"Physica C. 392-396. 82-86 (2003)
[Publications] M.Matvejeff, V.P.S.Awana, L.-Y.Jang, R.S.Liu, H.Yamauchi, M.Karppinen: "Oxygen non-stoichiometry in Ru-1212 and Ru-1222 magnetosuperconductors"Physica C. 392-396. 87-92 (2003)
[Publications] T.Watanabe, N.Kiryakov, J.Poulsen, J.M.Lee, J.M.Chen, R.S.Liu, H.Yamauchi, M.Karppinen: "XANES and wet-chemical analyses of the charge balance in (Hg, Pb)(Ba, Sr)_2Ca_2Cu_3O<8+δ>"Physica C. 392-396. 93-98 (2003)
[Publications] T.Nagai, V.P.S.Awana, E.Takayama-Muromachi, A.Yamazaki, M.Karppinen, H.Yamauchi, S.K.Malik, W.B.Yelon, Y.Matsui: "Structural order and disorder in Co-based layered cuprates CoSr_2(Y, Ce)_sCu_2O_<5+2s>(s=1-3)"Journal of Solid State Chemistry. 176. 213-220 (2003)
[Publications] V.P.S.Awana, A.Gupta, H.Kishan, E.Takayama-Muromachi, T.Watanabe, M.Karppinen, H.Yamauchi, S.K.Malik, W.B.Yelon, V.Ganesan, A.V.Narlikar: "Superconductivity with transition temperature up to 80 K for TbSr_2Cu_<2.7>Mo_<0.3>O_<7+δ>"Solid State Communications. 129. 117-121 (2003)
[Publications] G.Peleckis, T.Motohashi, M.Karppinen, H.Yamauchi: "Enhanced thermoelectric properties of Na_xCoO_2 : whisker crystals"Applied Physics Letters. 83. 5416-5418 (2003)
[Publications] V.P.S.Awana, M.Karppinen, H.Yamauchi: "Magneto-superconductivity in rutheno-cuprates RuSr_2GdCu_2O_<8-δ> (Ru-1212) and RuSr_2(Gd_<0.75>Ce_<0.25>)_2Cu_2O_<10-δ> (Ru-1222) : a critical review"In : International Book Series : Studies of High Temperature Superconductors, Vol.46, A.V.Narlikar (Ed.), Nova Science Publishers, New York 2003. 77-98 (2003)
[Publications] M.Karppinen, H.Yamauchi, Y.Morita, M.Kitabatake, T.Motohashi, R.S.Liu, J.M.Lee, J.M.Chen: "Hole concentration in the three-CuO_2-plane copper-oxide superconductor Cu-1223"Journal of Solid State Chemistry. (in press). (2004)
[Publications] T.Yokosawa, V.P.S.Awana, K.Kimoto, E.Takayama-Muromachi, M.Karppinen, H.Yamauchi, Y.Matsui: "Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors : RuSr_2Gd_<1.5>Ce_<0.5>Cu_2O_<10-δ> (Ru-1222) and RuSr_2GdCu_2O_8 (Ru-1212)"Ultramicroscopy. (in press). (2004)
[Publications] M.Karppinen, H.Okamoto, H.Fjellvag, T.Motohashi, H.Yamauchi: "Oxygen and cation ordered perovskite, Ba_2Y_2Mn_4O_<11>"Journal of Solid State Chemistry. (in press). (2004)
[Publications] T.Nakane, K.Isawa, R.S.Liu, J.M.Chen, H.Yamauchi, M.Karppinen: "Effect of Sr-for-Ba isovalent substitution on the local structure, hole distribution and magnetic irreversibility of Cu(Ba, Sr)_2YbCu_2O_<6.95(2)>"Journal of Solid State Chemistry. (in press). (2004)
[Publications] J.Linden, P.Karen, H.Yamauchi, M.Karppinen: "Valence mixing, separation and ordering in double-cell perovskite GdBaFe_2O_<5+w>"Hyperfine Interactions. (in press). (2004)
[Publications] M.Karppinen, I.Asako, T.Motohashi, H.Yamauchi: "Oxidation state of cobalt in the Na_xCoO_<2-δ>・y H_2O superconductor"Chemistry of Materials. (in press). (2004)

2003 Fiscal Year Annual Research Report

常温でハーフメタル状態を発現する層状酸化物の創製

Principal Investigator

山内 尚雄 東京工業大学, 応用セラミックス研究所, 教授 (50271581)

Research Products

[Publications] C.A.Cardoso, F.M.Araujo-Moreira, V.P.S.Awana, E.Takayama-Muromachi, O.F.de Lima, H.Yamauchi, M.Karppinen: "Spin glass behavior in RuSr_2Gd_<1.5>Ce_<0.5>Cu_2O_<10-δ>"Physical Review B. 67. R20407-R20410 (2003)

[Publications] T.Motohashi, R.Ueda, E.Naujalis, T.Tojo, I.Terasaki, T.Atake, M.Karppinen, H.Yamauchi: "Unconventional magnetic transition and transport behavior in Na_<0.75>CoO_2"Physical Review B. 67. 64406-64410 (2003)

[Publications] M.Karppinen, K.Kotiranta, T.Nakane, S.C.Chang, J.M.Chen, R.S.Liu, H.Yamauchi: "Layer-specific hole concentrations in Bi_2Sr_2(Y_<1-x>Ca_x)Cu_2O_<8+δ> as probed by XANES spectroscopy and coulometric redox analysis"Physical Review B. 67. 134522-134527 (2003)

[Publications] Y.Morita, M.Karppinen, H.Yamauchi, R.S.Liu, J.M.Chen: "XANES study on the evolution among different copper species, Cu^I, Cu^<II> and Cu^<III>, in CuBa_2YCu_2O_<6+z> upon Oxygen Loading"Journal of Low Temperature Physics. 131. 381-386 (2003)

[Publications] H.Yamauchi, M.Karppinen: "Relationship between local atomic arrangements and properties of high-T_c superconductive copper oxides"Journal of Low Temperature Physics. 131. 705-717 (2003)

[Publications] V.P.S.Awana, M.Karppinen, H.Yamauchi, M.Matvejeff, R.S.Liu, L.-Y.Jang: "Oxygen content and valence of Ru in RuSr_2(Gd_<0.75>Ce_<0.25>)_2Cu_2O_<10-δ>"Journal of Low Temperature Physics. 131. 1211-1216 (2003)

[Publications] V.P.S.Awana, E.Takayama-Muromachi, M.Karppinen, H.Yamauchi: "Magneto-superconductivity of 100-atm O_2-annealed RuSr_2Gd_<1.5>Ce<0.5>Cu_2O_<10-δ>"Physica C. 390. 233-238 (2003)

[Publications] J.Sugiyama, H.Itahara, J.H.Brewer, E.J.Ansaldo, T.Motohashi, M.Karppinen, H.Yamauchi: "Static magnetic order in Na_<0.75>CoO_2 detected by muon spin rotation and relaxation"Physical Review B. 67. 214420-214424 (2003)

[Publications] M.Karppinen, S.Lee, J.M.Lee, J.Poulsen, T.Nomura, S.Tajima, J.M.Chen, R.S.Liu, H.Yamauchi: "Hole doping in Pb-free and Pb-substituted (Bi, Pb)_2Sr_2Ca_2Cu_3O<10+δ> superconductors"Physical Review B. 68. 54502-54506 (2003)

[Publications] T.Motohashi, R.Ueda, E.Naujalis, T.Tojo, I.Terasaki, T.Atake, M.Karppinen, H.Yamauchi: "Unconventional electronic transition in Na_xCoO_2 with a precisely controlled Na nonstoichiometry"Physica B. 329-333. 914-915 (2003)

[Publications] Y.Morita, H.Yamauchi, M.Karppinen: "Superconductivity in CoSr_2(Y_<1-x>Ca_x)Cu_2O_<7+δ>"Solid State Communications. 127. 493-498 (2003)

[Publications] Y.Moritomo, M.Hanawa, Y.Ohishi, K.Kato, J.Nakamura, M.Karppinen, H.Yamauchi: "Physical pressure effect on the charge-ordering transition of BaSmFe_2O_<5.0>"Physical Review B. 68. R60101-R60104 (2003)

[Publications] M.Karppinen, V.P.S.Awana, Y.Morita, H.Yamauchi: "Oxygen stoichiometry in Co-1212, Co-1222 and Co-1232 of the homologous series Co-12s2 of "category-B" layered copper oxides"Physica C. 392-396. 82-86 (2003)

[Publications] M.Matvejeff, V.P.S.Awana, L.-Y.Jang, R.S.Liu, H.Yamauchi, M.Karppinen: "Oxygen non-stoichiometry in Ru-1212 and Ru-1222 magnetosuperconductors"Physica C. 392-396. 87-92 (2003)

[Publications] T.Watanabe, N.Kiryakov, J.Poulsen, J.M.Lee, J.M.Chen, R.S.Liu, H.Yamauchi, M.Karppinen: "XANES and wet-chemical analyses of the charge balance in (Hg, Pb)(Ba, Sr)_2Ca_2Cu_3O<8+δ>"Physica C. 392-396. 93-98 (2003)

[Publications] T.Nagai, V.P.S.Awana, E.Takayama-Muromachi, A.Yamazaki, M.Karppinen, H.Yamauchi, S.K.Malik, W.B.Yelon, Y.Matsui: "Structural order and disorder in Co-based layered cuprates CoSr_2(Y, Ce)_sCu_2O_<5+2s>(s=1-3)"Journal of Solid State Chemistry. 176. 213-220 (2003)

[Publications] V.P.S.Awana, A.Gupta, H.Kishan, E.Takayama-Muromachi, T.Watanabe, M.Karppinen, H.Yamauchi, S.K.Malik, W.B.Yelon, V.Ganesan, A.V.Narlikar: "Superconductivity with transition temperature up to 80 K for TbSr_2Cu_<2.7>Mo_<0.3>O_<7+δ>"Solid State Communications. 129. 117-121 (2003)

[Publications] G.Peleckis, T.Motohashi, M.Karppinen, H.Yamauchi: "Enhanced thermoelectric properties of Na_xCoO_2 : whisker crystals"Applied Physics Letters. 83. 5416-5418 (2003)

[Publications] M.Karppinen, H.Yamauchi, Y.Morita, M.Kitabatake, T.Motohashi, R.S.Liu, J.M.Lee, J.M.Chen: "Hole concentration in the three-CuO_2-plane copper-oxide superconductor Cu-1223"Journal of Solid State Chemistry. (in press). (2004)

[Publications] M.Karppinen, H.Okamoto, H.Fjellvag, T.Motohashi, H.Yamauchi: "Oxygen and cation ordered perovskite, Ba_2Y_2Mn_4O_<11>"Journal of Solid State Chemistry. (in press). (2004)

[Publications] T.Nakane, K.Isawa, R.S.Liu, J.M.Chen, H.Yamauchi, M.Karppinen: "Effect of Sr-for-Ba isovalent substitution on the local structure, hole distribution and magnetic irreversibility of Cu(Ba, Sr)_2YbCu_2O_<6.95(2)>"Journal of Solid State Chemistry. (in press). (2004)

[Publications] J.Linden, P.Karen, H.Yamauchi, M.Karppinen: "Valence mixing, separation and ordering in double-cell perovskite GdBaFe_2O_<5+w>"Hyperfine Interactions. (in press). (2004)

[Publications] M.Karppinen, I.Asako, T.Motohashi, H.Yamauchi: "Oxidation state of cobalt in the Na_xCoO_<2-δ>・y H_2O superconductor"Chemistry of Materials. (in press). (2004)

山内尚雄東京工業大学, 応用セラミックス研究所, 教授 (50271581)