Relationship between disorder, magnetism and band topology in Mn(Sb_1–x Bi _x )₂Te₄ single crystals

Abstract

We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb1-x Bi x )2Te4 single crystals grown by large-temperature-gradient chemical vapor transport method. It is found that the ferromagnetic MnSb2Te4 changes to antiferromagnetism with Bi doping when x ≥ 0.25. Further analysis implies that the occupations of Mn ions at Sb/Bi site MnSb/Bi and Mn site MnMn have a strong influence on the magnetic ground state of these systems. With the decrease of MnMn and increase of MnSb/Bi, the system will favor the ferromagnetic ground state. In addition, the rapid decrease of T C/N with increasing Bi content when x ≤ 0.25 and the insensitivity of T N to x when x > 0.25 suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida-type at low Bi doping region to the van-Vleck-type in high Bi doped samples.