Magnetic field induced enlargement of the regime of critical fluctuations in the classical superconductor V3Si from high-resolution specific heat experiments

TL;DR

High-resolution specific heat measurements on V3Si reveal magnetic field-induced enlargement of critical fluctuation regimes, evidenced by lambda anomalies and transition broadening, explained by fluctuation models and Landau level confinement.

Contribution

This study demonstrates that magnetic fields extend the observable critical fluctuation regime in V3Si, supported by scaling analysis based on 3d-XY and 3d-LLL models.

Findings

Lambda anomalies appear in high magnetic fields.

Critical fluctuations are enlarged by magnetic field.

Effective dimensionality reduction due to Landau levels.

Abstract

We report high-resolution specific heat data on a high-quality single crystal of the classical superconductor V3Si, which reveal tiny lambda-shape anomalies appearing superimposed onto the BCS specific heat jump at the superconducting transition in magnetic fields of 2 T and higher. The appearance of these anomalies is accompanied by a magnetic-field-induced broadening of the superconducting transition. We demonstrate, using scaling relations predicted by the fluctuation models of the 3d-XY and the 3d-Lowest-Landau-Level (3d-LLL) universality class, that the effect of critical fluctuations becomes experimentally observable due to of a magnetic field-induced enlargement of the regime of critical fluctuations. The scaling indicates that a reduction of the effective dimensionality due to the confinement of quasiparticles into low Landau levels is responsible for this effect.