NQR Studies on Magnetism and Superconductivity of Oxides Superconductors

氧化物超导体磁性和超导性的NQR研究

• 批准号: 63540267
• 负责人: KUMAGAI Ken-ichi
• 金额: $ 1.28万
• 依托单位: Faculty of Science, Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63540267/
• 关键词: Nuclear Magnetic Resonance; Nuclear Spin-Lattice Relaxation Time; High-T_c Superconductor; Antiferromagnetism; 磁気秩序

Nuclear quadrupole resonances (NQR) of ^<139>La and ^<63,65>Cu have been investigated in the wide range of x in hole-doped La_<2-x>M_xCuO_4 (M=Sr, Ba). The divergence of the nuclear relaxation rate of ^<139>La at T_c*-10K indicates the existence of the peculiar frustrated magnetic phase between the 3D-antiferro- magnetic and superconducting phases. The spin echo signals of ^<63,65>Cu are observed between 30-50KHz in zero external field. The spectra consist of the two component of the Cu-NQR lines for x<0.4, of which origin is still unclear. Relaxation rates, 1/T_1 and 1/T_2 are much enhanced with decreasing x. The temperature dependence of 1/T_1 for x>0.4 obeys the Korringa relation, T_1T=const., below 200K.We have confirmed the antiferromagntic order of Cu moments in the electron-doped Ln_<2-x>Ce_xCuO_4 (Ln =Nd, Pr, Sm). Unexpected observation of nuclear magnetic resonance (NMR) with vanishingly small quadrupole interactions in the Ce-doped samples suggests that the local electronic properties at Cu site in the electron-doped oxides differ from the hole-doped ones.

本文研究了空穴掺杂La_&lt；2-x&gt；M_xCuO_4(M=Sr，Ba)中^&lt；139&gt；La和^&lt；63，65&gt；Cu的核四极共振(NQR)。^&lt；139&gt；La在T_c~*-10K的核弛豫速率的发散表明，在3D反铁磁相和超导相之间存在着特殊的受挫磁相。在零外场条件下，在30-50 kHz范围内观察到了63，65&gt；Cu的自旋回波信号。光谱由x&lt；0.4的Cu-NQR谱线的两个分量组成，其来源尚不清楚。弛豫速率1/T_1和1/T_2随x的减小而显著增大。x&gt；0.4的1/T_1与温度的关系在200K以下服从Korringa关系，T_1T=const。我们确认了电子掺杂的Ln_&lt；2-x&gt；Ce_xCuO_4(Ln=Nd，Pr，Sm)中铜磁矩的反铁磁序。在Ce掺杂的样品中意外地观察到具有极小的四极相互作用的核磁共振(NMR)，这表明电子掺杂的氧化物中铜位的局域电子性质不同于空穴掺杂的氧化物。

项目成果

熊谷健一: Physica. 152C. 286-288 (1988)

熊谷健一：物理学152C 286-288（1988）。

渡辺功雄: "Effects of Oxygen and Magnetic Imputies on Nuclear Relaxation Anomalies in La-M-Cu-O System." J.Magnetism and Magnetic Materials. 76&77. 599-600 (1988)

Isao Watanabe：“氧和磁性杂质对 La-M-Cu-O 系统中核弛豫异常的影响。”J.Magnetism and Magnetic Materials 76&77 (1988)。

熊谷健一: Jpn.J.Appl.Phys.Series 1. 1. 37-41 (1988)

熊谷健一：Jpn.J.Appl.Phys.Series 1.1.37-41 (1988)

熊谷健一: "^<139>La-NQR and Heat Capacity of La_<2-x>M_xCuO_4(M=Ba,Sr)" Jpn.J.Appl.Phys.Series 1. 1. 37-41 (1988)

熊谷健一：“^<139>La-NQR 和 La_<2-x>M_xCuO_4(M=Ba,Sr) 的热容量” Jpn.J.Appl.Phys.Series 1. 1. 37-41 (1988)

渡辺功雄: J.Magnetism and Magnetic Materials. 76&77. 599-600 (1988)

渡边功：《磁学与磁性材料》76&77（1988）。