Critical currents, flux creep, and current-voltage characteristics of single crystals of the organic superconductor γ-(BEDT-TTF)2Cu[N(CN)2]Cl0.5Br0.5

The authors investigated, at normal pressure, single crystals of the organic superconductor γ-(BEDT-TTF)2Cu[N(CN)2]Cl0.5Br0.5 (x = 0.5) with the highest superconducting-transition temperature (∼12.5 K) of all organic superconductors. They obtained the temperature and field dependences of the critical current density, determined the anisotropy of the critical current, investigated the relaxation of the magnetic moment, and determined the dependence of the activation energy on the field. They calculated the current-voltage characteristics from the time dependences of the magnetic moment at a fixed temperature. They have found that the current-voltage characteristics can be described by either an exponential or a power-law E(j) dependence. 33 refs., 12 figs