Long-range supercurrents through a chiral non-collinear antiferromagnet in lateral Josephson junctions

Abstract

The proximity-coupling of a chiral non-collinear antiferromagnet (AFM) ^{1– 5} with a singlet superconductor allows spin-unpolarized singlet Cooper pairs to be converted into spin-polarized triplet pairs ^{6– 8} , thereby enabling non-dissipative, long-range spin correlations ^{9– 14} . The mechanism of this conversion derives from fictitious magnetic fields that are created by a non-zero Berry phase ¹⁵ in AFMs with non-collinear atomic-scale spin arrangements ^{1– 5} . Here we report long-ranged lateral Josephson supercurrents through an epitaxial thin film of the triangular chiral AFM Mn ₃Ge (refs. ^{3– 5} ). The Josephson supercurrents in this chiral AFM decay by approximately one to two orders of magnitude slower than would be expected for singlet pair correlations ^{9– 14} and their response to an external magnetic field reflects a clear spatial quantum interference. Given the long-range supercurrents present in both single- and mixed-phase Mn ₃Ge, but absent in a collinear AFM IrMn ¹⁶ , our results pave a way for the topological generation of spin-polarized triplet pairs ^{6– 8} via Berry phase engineering ¹⁵ of the chiral AFMs.

Abstract

Long-range lateral Josephson supercurrents are observed in a chiral non-collinear antiferromagnet, indicating topologically generated triplet pairing states.