Quasiparticle lifetime broadening and vortex dynamics in superconducting V₃Si single crystal

The A15 superconductor V₃Si – though the subject of nuclear magnetic resonance (NMR) studies for decades – continues to yield recent insights into its superconducting transition, as made possible by newer methods, the availability of high-quality, single-crystal samples, and access to temperatures down to the milliKelvin range. Building on recent updated understanding of the Martensitic transformation (MT) [Gapud et al., Physica C, vol. 602, 1354137], new data on the NMR longitudinal relaxation rate 1/T₁ has revealed interesting dependence on temperature and magnetic field across the superconducting transition and down below 100 mK – including a two-gap scenario, plus a field-dependent broadening of quasiparticle lifetimes inducing “edge smearing” in both gaps due to the incursion of vortices. Confidence in the T₁ measurement is due to the ability to align the sample along [111], as will be described.