Observation of Anomalous Hall Effect in Bulk Single Crystals of n-type Cr-doped Sb${}_2$Te${}_3$ Magnetic Topological Insulator

Abstract

The exploration of topological Dirac surface states is significant in the realms of condensed matter physics and future technological innovations. Among the materials garnering attention is Sb${}_2$Te${}_3$, a compound that theoretically exhibits topological insulating properties. However, its inherent p-type nature prevents the direct experimental verification of its Dirac surface state due to the Fermi level alignment with the valence band. In this study, by doping Cr atoms into Sb${}_2$Te${}_3$, n-type behavior is observed in the Hall resistance measurements. Remarkably, the Cr-doped Sb${}_2$Te${}_3$ not only shows ferromagnetism with a high transition temperature of approximately 170 K but also exhibits an anomalous Hall effect (AHE). The Cr doping also allows for a controlled method for Fermi level tuning into the band gap. These properties spotlight its potential as an n-type magnetic topological insulator (MTI) as well as a material candidate for the quantum anomalous Hall effect (QAHE), opening new avenues for applications in spintronics and quantum devices.