Inhaltszusammenfassung

The temperature T dependence of the normalized magnetization relaxation rate S in optimally doped YBa2Cu3O7?? films with the external dc magnetic field H oriented along the c axis exhibits the well-known plateau in the intermediate T range, associated with the presence of elastic (collective) vortex creep. The disappearance of the S(T) plateau in the high-H domain (H?20?kOe) is not completely understood. We show that in the case of high-temperature superconductors with significant quenched di...The temperature T dependence of the normalized magnetization relaxation rate S in optimally doped YBa2Cu3O7?? films with the external dc magnetic field H oriented along the c axis exhibits the well-known plateau in the intermediate T range, associated with the presence of elastic (collective) vortex creep. The disappearance of the S(T) plateau in the high-H domain (H?20?kOe) is not completely understood. We show that in the case of high-temperature superconductors with significant quenched disorder the S(T) plateau is directly related to a crossover in the vortex-creep process generated by the macroscopic currents induced in the sample. In dc magnetization measurements the creep-crossover temperature decreases rapidly with increasing H, reaching the low-T region where the magnetization decay is dominated by micro flux jumps. Consequently, at high H no well-defined elastic-creep domain is present and the S(T) plateau disappears.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
Physik der kondensierten Materie

DDC Sachgruppe:
Physik