Disorder-induced magnetoelastic behavior of MnTexSbyBi1-x-y alloys

Abstract

Compositional tuning between materials with contrasting magnetic and electronic properties can induce behaviors absent in their end members. In this paper, we demonstrate that in mixed MnTe-MnSb-MnBi alloy systems, the competition between MnTe, an antiferromagnetic (AFM) semiconductor with altermagnetic band symmetry, and the ferromagnetic (FM) metals MnSb and MnBi drives several composition-dependent transitions. Using first-principles calculations of disordered supercells we reveal that an AFM-FM boundary near MnTe0.75Sb0.25 exhibits a pronounced magnetoelastic response, disorder-induced phonon broadening, and a semiconductor-to-metal crossover. These effects are associated with enhanced fluctuations in local bonding and interatomic force constants near the AFM-FM crossover. This work elucidates how magnetic competition and local chemical disorder shape the structural, vibrational, and electronic behaviors of MnTexSbyBi1-x-y alloys, thereby driving large magnetoelastic responses.