Disorder-induced magnetism in amorphous MoS2 monolayer

Abstract

Using ab initio molecular dynamics combined with machine learning, we simulate bulk amorphous MoS2, where a layered structure forms, consisting of 1T-phase, 1H-phase, and defect regions. After extracting isolated monolayers from the evolving bulk structure, we investigate their structural and magnetic properties. Our simulations reveal that the 1T-phase region gradually diminishes over time, while the thermodynamically more stable 1H-phase region expands. The defect regions, interspersed between these phases, shift position as the system evolves. The inherent disorder in the amorphous structure leads to electron localization at Mo sites in some of the 1T-phase or defect regions, which induces spin polarization and results in the formation of localized magnetic moments. These magnetic moments exhibit both short-range antiferromagnetic and ferromagnetic couplings via a superexchange mechanism mediated by sulfur ligands, depending on the disordered local structures at different time points. In particular, the spin directions are noncollinear, with slight tilting from the out-of-plane axis that varies between Mo atoms. These findings highlight that the magnetic properties of the amorphous MoS2 monolayer can be tuned by modulating structural disorder and evolution, offering exciting prospects for applications in spintronics and magnetic technologies.