Reentrance of a flux liquid near Hc1 in high-Tc superconductors

Abstract

Previous studies by D. R. Nelson have demonstrated that flux-line wandering in high-Tc oxides in fields slightly above Hc1 leads to an entangled flux liquid. The statistical mechanics of the flux lines is isomorphic to a two-dimensional (2D) interacting quantum particle system with pairwise interaction potential V(r)=(φ02/8π2λ2)K0(r/λ), where λ is the magnetic penetration length and K0(x) is a modified Bessel function. We have performed a Monte Carlo simulation on the 2D interacting Bose system. The existence of a flux-liquid phase has been observed and the transtion line between flux liquid and flux solid has been identified for a crystalline sample of Y-Ba-Cu-O on the H-T phase diagram over a wide range of temperature. The width of the liquid phase increases with temperature as T2 at low temperatures, in agreement with the prediction of D. R. Nelson. At high temperatures the width of the liquid phase increases faster than T2. We argue that the melting curve eventually crosses over to the high-field vortex-lattice melting curve. Relevance to experiments on high-Tc superconductors is mentioned.

Source-reported materials — not catalogue approval

Similar papers