Thermodynamics of a Heavy Ion-Irradiated Superconductor: the Zero-Field Transition

TL;DR

This study investigates how amorphous columnar defects influence the superconducting transition in a superconductor without magnetic field, combining experimental specific heat measurements with numerical simulations to reveal changes in critical behavior.

Contribution

It demonstrates that columnar defects alter the universality class of the superconducting transition, supported by experimental data and numerical modeling of the 3D XY system.

Findings

Specific heat peak becomes smoother with defects

Numerical simulations match experimental trends

Columnar defects change the transition's universality class

Abstract

Specific heat measurements show that the introduction of amorphous columnar defects considerably affects the transition from the normal to the superconducting state in zero magnetic field. Experimental results are compared to numerical simulations of the 3D XY model for both the pure system and the system containing random columnar disorder. The numerics reproduce the salient features of experiment, showing in particular that the specific heat peak changes from cusp-like to smoothly rounded when columnar defects are added. By considering the specific heat critical exponent alpha, we argue that such behavior is consistent with recent numerical work [Vestergren et al., PRB 70, 054508 (2004)] showing that the introduction of columnar defects changes the universality class of the transition.