High Concentration Intrinsic Defects in MnSb₂Te₄.

Abstract

MnSb₂Te₄ has a similar structure to an emerging material, MnBi₂Te₄. According to earlier theoretical studies, the formation energy of Mn antisite defects in MnSb₂Te₄ is negative, suggesting its inherent instability. This is clearly in contrast to the successful synthesis of experimental samples of MnSb₂Te₄. Here, the growth environment of MnSb₂Te₄ and the intrinsic defects are correspondingly investigated. We find that the Mn antisite defect is the most stable defect in the system, and a Mn-rich growth environment favors its formation. The thermodynamic equilibrium concentrations of the Mn antisite defects could be as high as 15% under Mn-poor conditions and 31% under Mn-rich conditions. It is also found that Mn antisite defects prefer a uniform distribution. In addition, the Mn antisite defects can modulate the interlayer magnetic coupling in MnSb₂Te₄, leading to a transition from the ideal antiferromagnetic ground state to a ferromagnetic state. The ferromagnetic coupling effect can be further enhanced by controlling the defect concentration.