Mitigating Mn-Bi antisite pair defect formation in MnBi2Te4: the role of doping

MnBi₂Te₄ (MBT) is an intrinsically magnetic topological material which possesses unique properties due to quantum Hall effect. However, the low antisite pair defect formation energy between the Mn and Bi sites is detrimental to these properties as it alters the long range magnetic ordering in the Mn layer. For this end, we utilized a fisr principles based screening approach to understand the role of impurities in Mn and Bi sites to destabilize the Mn-Bi antisite pair defect formation energy. The results showed that certain elements, such as Sc and Y, tend to preferentially replace Bi atoms and significantly increase the energy required to form Mn-Bi antisite pair defects. However, none of the candidate dopants on the Mn site increase the Mn-Bi antisite formation energy, except for a small increase with Ni doping. Across all dopants, various local structural changes were found to influence the formation energy of Mn-Bi antisite defects, shedding light on the role of Sc and Y doping in this context.