Nonmagnetic Sn doping effect on the electronic and magnetic properties of antiferromagnetic topological insulator MnBi2Te4

Abstract

We investigated the effect of nonmagnetic Sn doping on the electronic and magnetic properties of antiferromagnetic topological insulator MnBi${}_2$Te${}_4$. We observe that the Sn doping reduces out-of-plane antiferromagnetic (AFM) interactions in Mn${}_{1-x}$Sn${}_x$Bi${}_2$Te${}_4$ for up to 68% of Sn concentration and above, the system is found to be a paramagnetic. In this way, the anomalous Hall effect observed at a very high critical field of 7.8 T in MnBi${}_2$Te${}_4$ is reduced to 2 T at 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 metal. Angle-resolved photoemission spectroscopy (ARPES) studies show that the topological properties are intact at least up to 55% of Sn doping as the Dirac surface states are present near the Fermi level. But in SnBi${}_2$Te${}_4$ we are unable to detect the surface states due to heavy hole doping. Thus, the Sn doping significantly affects the electronic and magnetic properties of MnBi${}_2$Te${}_4$.