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

TL;DR

This study reports the discovery of ferromagnetism in a van der Waals compound MnSb$_{1.8}$Bi$_{0.2}$Te$_4$, revealing its potential as a ferromagnetic topological insulator with unique magnetic and electrical properties.

Contribution

It demonstrates ferromagnetic order in MnSb$_{1.8}$Bi$_{0.2}$Te$_4$, contrasting with previous antiferromagnetic members, advancing the understanding of magnetic topological insulators.

Findings

Ferromagnetic ground state with T_C of 26 K

Observation of anomalous Hall effect

Distinct magnetic and electrical properties

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.