Effect of disorder on the vortex-lattice melting transition

TL;DR

This study investigates how disorder affects the vortex-lattice melting transition in high Tc superconductors, revealing that disorder transforms a first-order transition into two continuous transitions related to loss of superconductivity in different directions.

Contribution

It demonstrates that disorder splits the vortex-lattice melting transition into two separate continuous transitions, aligning with recent experimental observations.

Findings

Disorder destroys the first-order melting transition.

Two continuous transitions occur at different temperatures.

Superconductivity is lost in perpendicular and parallel directions at separate points.

Abstract

We use a three dimensional stacked triangular network of Josephson junctions as a model for the study of vortex structure in the mixed state of high Tc superconductors. We show that the addition of disorder destroys the first order melting transition occurring for clean samples. The melting transition splits in two different (continuous) transitions, ocurring at temperatures Ti and Tp (>Ti). At Ti the perpendicular-to-field superconductivity is lost, and at Tp the parallel-to-field superconductivity is lost. These results agree well with recent experiments in YBaCuO.