Effect of spin fluctuations on superconductivity in V and Nb: a first-principles study

TL;DR

This study uses first-principles calculations to quantify how spin fluctuations (paramagnons) suppress superconductivity in V and Nb, revealing their canceling effect on phonon-mediated pairing and Coulomb interactions.

Contribution

It introduces a non-empirical computational scheme based on density functional theory for superconductors to analyze spin fluctuation effects without empirical parameters.

Findings

Paramagnons significantly suppress $T_c$ in V and Nb.

Spin fluctuations cancel out phonon and Coulomb interaction effects.

The method accurately quantifies fluctuation impacts on superconductivity.

Abstract

We study the superconductivity in typical $d$-band elemental superconductors V and Nb with the recently developed non-empirical computational scheme based on the density functional theory for superconductors. The effect of ferromagnetic fluctuation (paramagnon) on the superconducting transition temperature ($T_{\rm c}$), which in principle suppress the $s$-wave superconducting pairing, is quantified without any empirical parameter. We show that the strong paramagnon effect cancels the $T_{\rm c}$-enhancing effects of the phonon-mediated pairing and dynamical screened Coulomb interaction.