Eliashberg study of superconductivity induced by interfacial coupling to antiferromagnets

TL;DR

This study uses Eliashberg theory to analyze magnon-mediated superconductivity at interfaces with antiferromagnets, revealing how pairing symmetry and critical temperature depend on doping and interface compensation.

Contribution

It provides new insights into the impact of interface compensation and magnon spectrum cutoff on the superconducting pairing symmetry and critical temperature.

Findings

$p$-wave pairing occurs at high doping with uncompensated interfaces.

$d$-wave pairing appears near half-filling with compensated interfaces.

The $d$-wave phase may sustain higher critical temperatures due to larger effective magnon cutoff.

Abstract

We perform Eliashberg calculations for magnon-mediated superconductivity in a normal metal, where the electron-magnon interaction arises from interfacial coupling to antiferromagnetic insulators. In agreement with previous studies, we find $p$-wave pairing for large doping when the antiferromagnetic interfaces are uncompensated, and $d$-wave pairing close to half-filling when the antiferromagnetic interfaces are compensated. However, for the $p$-wave phase, we find a considerable reduction in the critical temperature compared to previous weak-coupling results, as the effective frequency cutoff on the magnon propagator in this case is found to be much smaller than the cutoff on the magnon spectrum. The $d$-wave phase, on the other hand, relies less on long-wavelength magnons, leading to a larger effective cutoff on the magnon propagator. Combined with a large density of states close to half-filling, this might allow the $d$-wave phase to survive up to higher critical temperatures. Based on our findings, we provide new insight into how to realize interfacially induced magnon-mediated superconductivity in experiments.