Ferromagnetic van der Waals compound MnSb${}_{1.8}$Bi${}_{0.2}$Te${}_4$

Abstract

The intersection of topology and magnetism represents a new playground to discover novel quantum phenomena and device concepts. In this work, we show that a van der Waals compound MnSb${}_{1.8}$Bi${}_{0.2}$Te${}_4$ exhibits a ferromagnetic ground state with a Curie temperature of 26 K, in contrast to the antiferromagnetic order previously found for other members of the Mn(Sb, Bi)${}_2$Te${}_4$ family. We employ magneto-transport, bulk magnetization and neutron scattering studies to illustrate the magnetic and electrical properties of MnSb${}_{1.8}$Bi${}_{0.2}$Te${}_4$ and report on the observation of an unusual anomalous Hall effect. Our results are an important step in the synthesis and understanding of ferromagnetic topological insulators.