Triplet correlations in superconductor/antiferromagnet heterostructures: dependence on type of antiferromagnetic ordering

TL;DR

This paper develops a theory for proximity-induced triplet correlations in superconductor/antiferromagnet heterostructures with various magnetic orderings, revealing how the type of antiferromagnetic order influences the structure and strength of triplet correlations.

Contribution

It generalizes previous models to arbitrary two-sublattice antiferromagnetic orderings, clarifying which antiferromagnets induce specific triplet correlations and their possible structures.

Findings

Checkerboard Neel correlations dominate in collinear compensated antiferromagnets.

Layered antiferromagnets generate weaker layered Neel correlations.

Triplet correlations in layered antiferromagnets can resemble either Neel or ferromagnetic structures.

Abstract

In recent years, a number of studies have predicted the emergence of a nontrivial proximity effect in superconductor/antiferromagnet (S/AF) heterostructures. This effect is of considerable interest for the efficient integration of antiferromagnetic materials into the fields of superconducting spintronics and electronics. A key element of this proximity effect is the Neel triplet correlations, initially predicted for S/AF heterostructures with checkerboard G-type antiferromagnetic ordering. However, various forms of antiferromagnetic ordering exist, and an important open question concerns the generalization of these results to such cases. In this paper, we develop a theory of the proximity effect in S/AF heterostructures with arbitrary two-sublattice antiferromagnetic ordering, aiming to clarify which antiferromagnets are capable of inducing triplet correlations and what structure these correlations may exhibit. We show that, in S/AF heterostructures with collinear compensated antiferromagnets, the dominant superconducting triplet correlations are of the checkerboard Neel type, as originally predicted for G-type antiferromagnets. In contrast, layered Neel triplet correlations, although potentially generated by layered antiferromagnets, are significantly weaker. Consequently, in S/AF heterostructures with layered antiferromagnetic ordering, the proximity-induced triplet correlations may exhibit either a checkerboard Neel or a conventional ferromagnetic structure, depending on the specific antiferromagnet and its orientation relative to the S/AF interface.