Evidence of magnetism-induced topological protection in the axion insulator candidate EuSn ₂ P ₂

Abstract

We unravel the interplay of topological properties and the layered (anti)ferromagnetic ordering in EuSn₂P₂, using spin and chemical selective electron and X-ray spectroscopies supported by first-principle calculations. We reveal the presence of in-plane long-range ferromagnetic order triggering topological invariants and resulting in the multiple protection of topological Dirac states. We provide clear evidence that layer-dependent spin-momentum locking coexists with ferromagnetism in this material, a cohabitation that promotes EuSn₂P₂ as a prime candidate axion insulator for topological antiferromagnetic spintronics applications.