Microwave Response of V3Si Single Crystals: Evidence for Two-Gap Superconductivity

TL;DR

This study investigates the microwave properties of V3Si single crystals, providing evidence for two-gap superconductivity through temperature-dependent measurements that contradict single-gap BCS theory.

Contribution

It presents experimental evidence supporting two-gap superconductivity in V3Si, modeled successfully by a two-band approach, challenging traditional single-gap theories.

Findings

Observation of peculiar temperature dependences incompatible with single-gap BCS theory.

Data well described by a two-band superconductivity model.

Identification of two distinct energy gaps, Delta1~1.8Tc and Delta2~0.95Tc.

Abstract

The investigation of the temperature dependences of microwave surface impedance and complex conductivity of V3Si single crystals with different stoichiometry allowed to observe a number of peculiarities which are in remarkable contradiction with single-gap Bardeen-Cooper-Schrieffer theory. At the same time, they can be well described by two-band model of superconductivity, thus strongly evidencing the existence of two distinct energy gaps with zero-temperature values Delta1~1.8Tc and Delta2~0.95Tc in V3Si.