Defective Vortex Lattices in Layered Superconductors with Point Pins at the Extreme Type-II Limit

摘要

The mixed phase of layered superconductors with no magnetic screening isstudied through a partial duality analysis of the corresponding frustrated XYmodel in the presence of weak random point pins. Isolated layers exhibit adefective vortex lattice at low temperature that is phase coherent.Sufficiently weak Josephson coupling between adjacent layers results in anentangled vortex solid that exhibits weak superconductivity across layers. Thecorresponding vortex liquid state shows an inverted specific heat anomaly thatwe propose accounts for that seen in YBCO. A three-dimensional vortex latticewith dislocations occurs at stronger coupling. This crossover sheds light onthe apparent discrepancy concerning the observation of a vortex-glass phase inrecent Monte Carlo simulations of the same XY model.