NMR Study on Metal-Insulator Transition and High T_C Superconductivity

金属-绝缘体转变和高温超导的核磁共振研究

• 批准号: 08044045
• 负责人: KUMAGAI Kenichi
• 金额: $ 1.41万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044045/
• 关键词: NMR; Oxide; High-T_c superconductivity; strongly correlated electron system; metal-insulator transition; YNi_2B_2C; spinel compound

In this project, unusual electronic properties of the strongly correlated systems such as quaternary compound YNi_2B_2C and RPt_2B_2C have been investigated by NMR measurement at both Zurich university and Hokkaido university. The enhancements of T_1T and Knight shift of ^<11>B at low temperature are not attributed to the effect of 3d spin fluctuations in the superconducting YNi_2B_2C families, but are attributed to peculiarities of their band structure.We have also prepared some Cu spinel compound of CuIr_2S_4 which shows metal-insulator (MI) transition. Sample of CuIr_2S_4 with enriched isotope of ^<33>S are prepared with collaboration of Russian group. From the results of line width and Knight shift of Cu-NMR,we confirmed no magnetic moment in the insulating state of CuIr_2S_4. We obtained also phase diagram of the MI transition of CuIr_2 (S_<1-x>Se_x)_4. Magnetic and local electronic states at the Metal-Insulator transition have been discussed and presented at the International Conference of Materials and Mechanism of High Tc-Superconductivity at Beijing.

本项目在苏黎世大学和北海道大学用核磁共振方法研究了四元化合物YNi_2B_2C和RPt_2B_2C等强关联体系的异常电子性质。低温下^ B的T_1 T和Knight位移的增强<11>不是由于YNi_2B_2C族超导体的3d自旋涨落的影响，而是由于它们的能带结构的特殊性。与<33>俄罗斯研究组合作，制备了富含硫同位素的CuIr_2S_4样品。从Cu-NMR的线宽和奈特位移的结果来看，我们证实CuIr_2S_4在绝缘状态下没有磁矩。我们还得到了CuIr_2（S_<1-x>Se_x）_4的MI跃迁相图。在北京举行的高Tc超导材料与机理国际会议上，讨论了金属-绝缘体转变的磁态和局域电子态。

项目成果

Tsuji, K.Kumagai, M.Kato, and Y.Koike: "NMR Study on Spin Gap in Spin Ladder Sr_<14>Cu_<24>O_<41>." J.Phys.Soc.Jpn.65. 3474-3477 (1996)

Tsuji、K.Kumagai、M.Kato 和 Y.Koike：“自旋梯 Sr_<14>Cu_<24>O_<41> 中自旋间隙的 NMR 研究。”

K.Kumagai,S.Ikeda,J.Roos,M.Mail and D.Brinkman: "^<195>Pt and ^<11>B NMR Study of LaPt_2B_2C and YNi_2B_2C" Physica. C272. 301-308 ((1996))

K.Kumagai、S.Ikeda、J.Roos、M.Mail 和 D.Brinkman：“LaPt_2B_2C 和 YNi_2B_2C 的 ^<195>Pt 和 ^<11>B NMR 研究”物理学。

S.Ikeda,K.Kumagai,J.Jiang,C.C.Lai,and H.C.Ku: "NMR Study of Quaternary Superconductors RT_2B_2C (R=Y,La,Th and T=Ni,Pd,Pt)" Physica. C263. 526-529 (1996)

S.Ikeda、K.Kumagai、J.Jiang、C.C.Lai 和 H.C.Ku：“四元超导体 RT_2B_2C（R=Y、La、Th 和 T=Ni、Pd、Pt）的核磁共振研究”物理学。

S.Ikeda, K.Kumagai, J.Jiang, M.S.Lin, C.C.Lai, and H.C.Ku: "NMR Study of Quaternary Superconductors RT_2B_2C (R=Y,La, Th and T=Ni, pd, pt)" Physica C. C272. 301-308 (1996)

S.Ikeda、K.Kumagai、J.Jiang、M.S.Lin、C.C.Lai 和 H.C.Ku：“四元超导体 RT_2B_2C (R=Y、La、Th 和 T=Ni、pd、pt) 的核磁共振研究” Physica C.

A.Yamanaka,K.Kumagai,Y.Piskunov and A.Yakubovsky,: "Hyperfine Field and Electric Field Gradient at Various Cation Sites in RBa_2Cu_2NbO_8 and RSr_2Cu_2GaO_7" J.Phys.Soc.Jpn.65. 3336-3342 ((1996))

A.Yamanaka、K.Kumagai、Y.Piskunov 和 A.Yakubovsky，“RBa_2Cu_2NbO_8 和 RSr_2Cu_2GaO_7 中不同阳离子位点的超精细场和电场梯度”J.Phys.Soc.Jpn.65。