Local and macroscopic tunneling spectroscopy of Y1-xCaxBa2Cu3O7-delta films: Evidence for a doping-dependent is or id(xy) component in the order parameter

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    TIME-REVERSAL SYMMETRY;    D-WAVE SUPERCONDUCTORS;    T-C SUPERCONDUCTORS;    SURFACE-STATES;    ANISOTROPIC SUPERCONDUCTORS;    CUPRATE SUPERCONDUCTORS;    PAIRING SYMMETRY;    BOUND-STATES;    JUNCTIONS;   

DOI  :  10.1103/PhysRevB.65.134526

来源: SCIE

【 摘 要 】

Tunneling spectroscopy of epitaxial (110) Y1-xCaxBa2Cu3O7-delta films reveals a doping-dependent transition from a pure d(x)(2)-y(2) to d(x)(2)-y(2)+is or d(x)(2)-y(2)+id(xy) order parameter. The subdominant (is or id(xy)) component manifests itself in a splitting of the zero-bias conductance peak and the appearance of subgap structures. The splitting is seen in the overdoped samples, increases systematically with doping, and is found to be an inherent property of the overdoped films. It was observed in both local tunnel junctions, using scanning tunneling microscopy (STM), and in macroscopic planar junctions, for films prepared by either sputtering or laser ablation. The STM measurements exhibit a fairly uniform splitting size in [110] oriented areas on the order of 10 nm(2) but vary from area to area, indicating some doping inhomogeneity. U- and V-shaped gaps were also observed, with good correspondence to the local faceting, a manifestation of the dominant d-wave order parameter.

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