Effect on the Electronic and Magnetic Properties of Antiferromagnetic Topological Insulator MnBi$_2$Te$_4$ with Sn Doping

TL;DR

This study explores how nonmagnetic Sn doping alters the electronic and magnetic properties of the antiferromagnetic topological insulator MnBi$_2$Te$_4$, revealing reduced AFM interactions, increased electron doping, and preserved topological states up to certain doping levels.

Contribution

It provides a comprehensive analysis of Sn doping effects on MnBi$_2$Te$_4$, including magnetic suppression, electron doping, and topological state preservation, which was not previously detailed.

Findings

Sn doping reduces AFM interactions significantly.

Sn doping increases electron carrier density by two orders.

Topological surface states remain intact up to 55% Sn doping.

Abstract

We thoroughly investigate the effect of nonmagnetic Sn doping on the electronic and magnetic properties of antiferromagnetic topological insulator MnBi$_2$Te$_4$. We observe that Sn doping reduces the out-of-plane antiferromagnetic (AFM) interactions in MnBi$_2$Te$_4$ up to 68\% of Sn concentration and above the system is found to be paramagnetic. In this way, the anomalous Hall effect observed at a very high field of 7.8 T in MnBi$_2$Te$_4$ is reduced to 2 T with 68\% of Sn doping. Electrical transport measurements suggest that all compositions are metallic in nature, while the low-temperature resistivity is sensitive to the AFM ordering and to the doping-induced disorder. Hall effect study demonstrates that Sn actually dopes electrons into the system, thus, enhancing the electron carrier density almost by two orders at 68\% of Sn. In contrast, SnBi$_2$Te$_4$ is found to be a p-type system. Angle-resolved photoemission spectroscopy (ARPES) studies show that the topological properties are intact at least up to 55\% of Sn as the Dirac surface states are present in the valance band, but in SnBi$_2$Te$_4$ we are unable to detect the topological states due to heavy hole doping. Overall, Sn doping significantly affects the electronic and magnetic properties of MnBi$_2$Te$_4$.