Thermodynamics of the vortex liquid in heavy-ion-irradiated superconductors | |
Article | |
关键词: HIGH-TEMPERATURE SUPERCONDUCTORS; BOSE-GLASS TRANSITION; COLUMNAR DEFECTS; CORRELATED DISORDER; II SUPERCONDUCTORS; SINGLE-CRYSTALS; UNTWINNED YBA2CU3O7-DELTA; YBACUO CRYSTALS; EQUILIBRIUM MAGNETIZATION; HIGH-DENSITY; | |
DOI : 10.1103/PhysRevB.72.214504 | |
来源: SCIE |
【 摘 要 】
It is shown that the large effect of heavy ion irradiation on the thermodynamical properties of the anisotropic superconductor YBa2Cu3O7-delta extends well into the superconducting fluctuation regime. The presence of the induced amorphous columnar defects shifts the specific-heat maximum at the normal-to-superconducting transition. This effect is similar to that recently put into evidence in cubic KxBa1-xBiO3 (x similar or equal to 0.35). In both compounds, vortex pinning manifests itself as a sharp angular dependence of the equilibrium torque. In YBa2Cu3O7-delta, pinning by the defects appears at the temperature T-Cp(max) of the specific-heat maximum, well above the magnetic irreversibility line T-irr(H). In isotropic KxBa1-xBiO3, the onset of the pinning-related torque anomaly tracks the onset of the specific-heat anomaly and the irreversibility line. In YBa2Cu3O7-delta, fluctuations of the amplitude of the order parameter (and not vortex line wandering) are ultimately responsible for the vanishing of pinning. In KxBa1-xBiO3, vortex pinning disappears only at the superconducting-to-normal transition. The results indicate that in both compounds, the pinning energy at the Bose-glass transition is large with respect to the total free energy gain in the superconducting state. By implication, the mechanism of this latter transition should be reconsidered.
【 授权许可】
Free