Relaxation in bulkRBa2Cu3O7−δsuperconductors

Abstract

The shape of the magnetic hysteresis curve, “MHL,” in bulk strongly doped $R{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ materials is analyzed and its correlation with relaxation characteristics is verified. It is shown that field and temperature dependencies of logarithmic relaxation rate, $Q=d\ln J∕d\ln dB∕dt$, can be obtained from $J\left(B\right)$ and $J\left(T\right)$ data ($J$ is the supercurrent density associated with total magnetic moment). In the case of the MHL with two well-distinguished peaks, the two additive contributions to $J$ are correlated with corresponding relaxation characteristics, which are given analytically. Plateau in $Q\left(T\right)$ dependence in such materials is shown to originate from scanning the specific shape of MHL at a fixed field. From $Q\left(J\right)$ plot pinning energy characteristics at low and intermediate fields are deduced.