Anomalous inverse proximity effect in unconventional-superconductor junctions

TL;DR

This paper explores how unconventional pairing and Andreev bound states influence the inverse proximity effect in ferromagnet/superconductor junctions, revealing conditions for magnetization inversion that can help identify pairing symmetry.

Contribution

It demonstrates that Andreev bound states and spin-mixing angles determine the direction of induced magnetization, providing new insights into the inverse proximity effect in unconventional superconductors.

Findings

Presence of Andreev bound states reverses magnetization direction.

Induced magnetization depends on spin-mixing angle.

Conditions for inverted magnetization are clarified.

Abstract

We investigate the effects of Andreev bound states due to the unconventional pairing on the inverse proximity effect of ferromagnet/superconductor junctions. Utilizing quasiclassical Eilenberger theory, we obtain the magnetization penetrating into the superconductor. We show that in a wide parameter range the direction of the induced magnetization is determined by two factors: whether Andreev bound states are present at the junction interface and the sign of the spin-mixing angle. In particular, when Andreev bound states appear at the interface, the direction of the induced magnetization is opposite to that without Andreev bound states. We also clarify the conditions under which the inverted induced magnetization appears. Applying this novel effect helps distinguishing the pairing symmetry of a superconductor.