Strain-driven phase transition and spin polarization of Re-doped transition-metal dichalcogenides

Abstract

Two-dimensional transition metal dichalcogenides (TMDCs) are promising in spintronics due to their spin–orbit coupling, but their intrinsic non-magnetic properties limit their further development. Here, we focus on the energy landscapes of TMDC (MX₂, M = Mo, W and X = S, Se, Te) monolayers by rhenium (Re) substitution doping under axial strains, which controllably drive 1H ↔ 1T_d structural transformations. For both 1H and 1T_d phases without strain, Re-doped TMDCs have an n-type character and are non-magnetic, but the tensile strain could effectively induce and modulate the magnetism. Specifically, 1H-Re_0.5Mo_0.5S₂ gets a maximum magnetic moment of 0.69 μ_B at a 6% uniaxial tensile strain along the armchair direction; along the zigzag direction it exhibits a significant magnetic moment (0.49 μ_B) at a 2.04% uniaxial tensile strain but then exhibits no magnetism in the range of [5.10%, 7.14%]. By contrast, for 1T_d-Re_0.5Mo_0.5S₂ a critical uniaxial tensile strain along the zigzag direction reaches up to ∼9.18%, and a smaller uniaxial tensile strain (∼5.10%) along the zigzag direction is needed to induce the magnetism in 1T_d-Re_0.5M_0.5Te₂. The results reveal that the magnetism of Re-doped TMDCs could be effectively induced and modulated by the tensile strain, suggesting that strain engineering could have significant applications in doped TMDCs.