Entropy jump at the first-order vortex phase transition in Bi2Sr2CaCu2O8+{\delta} with columnar defects

TL;DR

This study investigates the entropy change at the vortex melting transition in Bi2Sr2CaCu2O8+{eta} crystals with columnar defects, revealing how disorder affects the transition and comparing experimental results with theoretical models.

Contribution

It provides the first detailed measurement of entropy jumps at the vortex transition in crystals with columnar defects and compares these with theoretical predictions.

Findings

Entropy jump decreases with increased columnar defect density.

Pristine samples follow electromagnetic coupling theory, while defected samples deviate.

Disorder influences the vortex melting transition behavior.

Abstract

We study the entropy jump associated with the first-order vortex melting transition (FOT) in Bi2Sr2CaCu2O8+{\delta} crystals by means of Hall probe magnetometry. The samples present a diluted distribution of columnar defects (CD) introduced by irradiation with Xe ions. The FOT is detected in ac transmittivity measurements as a paramagnetic peak, the height of which is proportional to the enthalpy difference entailed by the transition. By applying the Clausius-Clapeyron relation, we quantify the evolution of the entropy jump {\Delta}s as a function of the FOT temperature, TFOT, in both pristine crystals and crystals with CD. On increasing the density of CD, {\Delta}s decreases monotonically with respect to values found in pristine samples. The {\Delta}s versus TFOT dependence in the case of pristine samples follows reasonably well the theoretical prediction of dominant electromagnetic coupling for a model neglecting the effect of disorder. The data for samples with a diluted distribution of CD are not properly described by such a theoretical model.