Static and Dynamic Vortex Phases in YBa2Cu3O7-delta (original) (raw)

Simultaneous magnetization, resistivity, and I-V measurements on YBa 2 Cu 3 O 72d show the relationship of the thermodynamic and dynamic behavior near the vortex lattice melting line. We find a coexistence region of solid and liquid at melting, with a first order magnetization jump which is independent of the vortex velocity. Sudden jumps and time dependent hysteresis of the I-V curve in the vortex solid phase are interpreted as a relaxation-pinning effect. [S0031-9007(96)01110-6] PACS numbers: 74.60. Ge, 74.25.Bt, 74.72.Bk The vortex system in high temperature superconductors is characterized by a vortex liquid phase that covers a large area in the field-temperature plane. For clean systems the transition into the vortex solid phase has been predicted to be first order , whereas in the presence of pinning induced disorder this transition is believed to be continuous, possibly to a vortex glass or Bose glass . For high quality YBa 2 Cu 3 O 72d and Bi 2 Sr 2 CaCu 2 O 8 single crystals sharp features in the resistivity [6] and discontinuous jumps in the magnetization [7-11] indicate a first order vortex transition. For both materials it is observed that the vortex melting transition is icelike, that is, the vortex density in the liquid is higher than in the solid.