Possible Origin of Anisotropic Resistive Hysteresis in the Vortex State of Untwinned YB${\mathrm{a}}_2$C${\mathrm{u}}_3$${\mathrm{O}}_7$ Single Crystals

The origin of resistive hysteresis in untwinned YB${\mathrm{a}}_2$C${\mathrm{u}}_3$ ${\mathrm{O}}_7$ single crystals is investigated for time scales from 1 to 1$0^3$ sec and for frequencies from 1$0^1$ to 1$0^6$ 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.