Vortex dynamics across the second-peak field in SmLa0.8Sr0.2CuO4−δ

Abstract Measurements of the temperature- and field-dependent magnetic relaxation data have been conducted on a superconducting T ∗ -phase SmLa 0.8 Sr 0.2 CuO 4− δ crystal in the vicinity of the second-peak field. The experimental data were analyzed to determine the current-dependent energy barrier, U ( J ), following a method proposed by Maley et al. The result was further investigated on the basis of weak collective pinning theory. It was found that the result of analysis on the temperature-dependent data was consistent with the theoretical description of thermal-disorder induced-interlayer-decoupling transition of the vortices, while its field-dependent data reveal the characteristic feature of elastic–plastic crossover of the vortex motion.