Colossal magnetoresistance in a nonsymmorphic antiferromagnetic insulator

Abstract

Here we investigate antiferromagnetic Eu${}_5$In${}_2$Sb${}_6$, a nonsymmorphic Zintl phase. Our electrical transport data show that Eu${}_5$In${}_2$Sb${}_6$ is remarkably insulating and exhibits an exceptionally large negative magnetoresistance, which is consistent with the presence of magnetic polarons. From {\it ab initio} calculations, the paramagnetic state of Eu${}_5$In${}_2$Sb${}_6$ is a topologically nontrivial semimetal within the generalized gradient approximation (GGA), whereas an insulating state with trivial topological indices is obtained using a modified Becke-Johnson potential. Notably, GGA+U calculations suggest that the antiferromagnetic phase of Eu${}_5$In${}_2$Sb${}_6$ may host an axion insulating state. Our results provide important feedback for theories of topological classification and highlight the potential of realizing clean magnetic narrow-gap semiconductors in Zintl materials.

arXiv commentAccepted in npj Quantum Materials. Author list and affiliations corrected

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