2024/10/08 by Guo, Yehao, Qiu, Dong, Liu, Haiwen +1 · 1 citation
#FOS: Physical sciences #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2410.05671
Despite a long history of Nernst effect in superconductors, a satisfactory theory on its amplitude in vortex liquid phase is still absent. The central quantity of vortex Nernst signals is the entropy sϕ carried by each vortex. Here we show a semiclassical treatment based on London equation and Pippard nonlocal generalization. The derived sϕ is a function of both temperatures and magnetic fields. Its magnitude sϕamp scales with normal-state conductivity σn. Estimations based on our formula show good consistency with experimentally determined values. In dirty limit, the relation is further simplified into a Wiedemann-Franz-like ratio sϕamp/σn ∝ kB ln 2/σQ if taking parameter values deduced from Homes' law, where σQ=4e2/h is two-dimensional quantum conductivity. We also address related issues, including bounds to sϕ, the Nernst signal and viscosity-entropy density ratio, which are all expressed in fundamental physical constants.