Temperature and magnetic-field dependence of quantum creep in various high-T-c superconductors

Article

关键词: THERMAL-CONDUCTIVITY;    SINGLE-CRYSTALS;    VORTEX DYNAMICS;    FLUX-CREEP;    BULK SUPERCONDUCTORS;    ACTIVATION-ENERGIES;    YBA2CU4O8 FILMS;    FALSE VACUUM;    THIN-FILMS;    RELAXATION;   

DOI  :  10.1103/PhysRevB.59.7222

来源: SCIE

【 摘 要 】

To investigate the quantum tunneling of almost macroscopic vortex segments we measured the normalized relaxation rate Q of superconducting currents for various high-T-c superconductors (HTS's) down to 100 mK in magnetic fields up to 7 T. At fields below congruent to 0.5 T, Q is essentially independent of T in the temperature regime between thermally activated and quantum motion as theoretically expected. However, at higher fields, we find an unexpected linear T dependence of Q persisting down to the lowest temperatures in all investigated samples. Since these compounds were chosen to represent the distinct classes of dirty and clean HTS's, the extrapolated Q(T = 0) values are used to discuss the theoretical models for quantum creep in the clean and dirty limits. Based on this discussion we propose a semiempirical interpolation formula for Q(T = 0) which is also valid for compounds in between the dirty and clean limits. [S0163-1829(99)00806-1].

【 授权许可】

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