Nonlocal conductance via overlapping Andreev bound states in ferromagnet-superconductor heterostructures

TL;DR

This paper investigates how overlapping Andreev bound states in ferromagnet-superconductor heterostructures influence nonlocal conductance, revealing dependence on interface distance and magnetization orientation, with implications for quantum transport phenomena.

Contribution

It introduces a detailed analysis of the interaction of Andreev bound states across interfaces, highlighting their impact on nonlocal conductance in ferromagnet-superconductor systems.

Findings

Andreev bound states depend on interface distance and magnetization orientation.

Distinct peaks in nonlocal conductance relate to bound state interactions.

Asymmetries in conductance are observed with voltage variations.

Abstract

In a setup where two ferromagnetic electrodes are attached to a superconductor, Andreev bound states are induced at both ferromagnet/superconductor (FM/SC) interfaces. We study how these states propagate through the SC and interact with each other. As a result of this interaction, the energetic positions of the Andreev states are not anymore determined solely by the magnetic properties of a single interface, but also depend on the interface distance and the relative magnetization orientation of the FM contacts. We discuss how these bound states show up as distinct peaks in the nonlocal conductance signal, and lead to marked asymmetries with respect to the applied voltage. We relate our results to nonlocal crossed Andreev and elastic co-tunneling processes.