POSSIBLE ORIGIN OF ANISOTROPIC RESISTIVE HYSTERESIS IN THE VORTEX STATE OF UNTWINNED YBA2CU3O7 SINGLE-CRYSTALS

The origin of resistive hysteresis in untwinned YBa2Cu3O7 single crystals is investigated for time scales from 1 to 103 sec and for frequencies from 101 to 106 Hz. The absence of resistive subloops upon partial heating and cooling, the lack of time dependence, and the decreasing hysteresis with the increasing angle between the applied magnetic field and crystalline c axis suggest that the hysteresis is not a direct evidence of a first-order vortex-solid melting transition. A current-induced nonequilibrium effect is proposed as the possible origin for the hysteresis. © 1995 The American Physical Society.