Metastability of the vortex solid in detwinned YBa2Cu3Oy

Pronounced history dependences have been observed in the transport characteristics of YBa2 CU3Oy Single crystals for temperatures and fields below the thermodynamic melting line, By using an annealing current to control the point at which the vortex system is exposed to the underlying disorder potential, we have been able to probe the competition between pinning, thermal and vortex-vortex interactions across the melting transition. In this way we have shown that in field cooled measurements, the majority of pinning in the vortex solid state arises due to processes occurring in a narrow region just below the melting temperature. (C) 2000 Elsevier Science B.V. All rights reserved.