Ferromagnetic semiconductor and strain-switchable metal-insulator transition in Mo₁₂S₉I₉ nanowires

Low-dimensional magnetic semiconductor systems remain rare but essential for realizing spintronic devices. Using first-principles calculations, we discover that MoSI nanowire is a magnetic semiconductor with multi-stability and possesses a rich strain-responsive phase diagram. An axial compressive strain induces a phase transition to a distinct metastable magnetic semiconductor phase and an easy magnetic axis swap from the perpendicular to the axial direction. Remarkably, under an axial tensile strain, the system undergoes a first-order Mott-Hubbard-like phase transition from a magnetic semiconductor into a metastable non-magnetic metal phase. This ability to reversibly switch between magnetic semiconductors with tailored anisotropy, and the strain-tunability of the Mott-Hubbard transition, underscore MoSI nanowire as a highly promising platform for adaptive nanoelectronics, strain-sensitive magneto-devices, and phase-change applications.