Superconducting fluctuations and anomalous diamagnetism in underdoped YBa2Cu3O6+x from magnetization and Cu-63 NMR-NQR relaxation measurements

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    YBA2CU3O7-DELTA SINGLE-CRYSTALS;    D-WAVE SUPERCONDUCTIVITY;    T-C SUPERCONDUCTORS;    NORMAL-STATE;    SPIN SUSCEPTIBILITY;    FIELD;    GAP;    PSEUDOGAP;    BEHAVIOR;   

DOI  :  10.1103/PhysRevB.61.12420

来源: SCIE

【 摘 要 】

Magnetization and Cu-63 nuclear magnetic resonance-nuclear quadrupole resonance relaxation measurements are used to study the superconducting fluctuations in YBa2Cu3O6+x (YBCO) oriented powders. In optimally doped YBCO the fluctuating negative magnetization M-fl(H,T) is rather well described by an anisotropic Ginzburg-Landau (GL) functional and the curves M-fl/root H cross at T-c. In underdoped YBCO, instead, over a wide temperature range an anomalous diamagnetism is observed, stronger than in the optimally doped compound by about an order of magnitude. The field and temperature dependence of Mfi cannot be described either by an anisotropic GL functional or on the basis of scaling arguments. The anomalous diamagnetism is more pronounced in samples with a defined order in the Cu(1)O chains. The Cu-63(2) relaxation rate shows little, if any, field dependence In the vicinity of the transition temperature T-c(N=0). It is argued how the results in the underdoped compounds can be accounted for by the presence of charge inhomogeneities, favored by chains ordering.

【 授权许可】

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