102 / 2021-07-12 16:28:01

Strain-Controllable Phase and Magnetism Transitions in Re-Doped MoTe2 Monolayer

phase transition, transition metal dichalcogenides, doping

Developing approaches to effectively manipulate the magnetic states and phase transition is critical to the application of transition metal dichalcogenides (TMDs) in spintronic or phase switching devices. Because of the small energy difference between semiconducting 2H-MoTe₂ and semimetallic 1T′-MoTe₂, fast on/off switching through phase transition could be realized in MoTe₂-based devices. In this work, Re doping and strain engineering are combined to control the phase transition between 2H- and 1T′-MoTe₂ and to induce magnetism in the system based on density functional theory calculations. The structural transformation from 2H- to 1T′- phase is predicted to occur around a doping concentration of 11%. The intrinsically nonmagnetic 2H-MoTe₂ structures with various doping concentrations become magnetic under a biaxial tensile strain, and the magnetic moment slowly increases with strain. For 1T′- MoTe₂, only monolayers with a doping concentration of less than 10% exhibit magnetism under relatively high strain. The conversion from ionic to covalent bonding and the self-exchange mechanisms are found to be the origin of the tunable magnetic behaviors under strain. Thus, a magnetic 1T′ state and a nonmagnetic 2H state in Mo_1-xRe_xTe₂ monolayers can be switched by strain engineering. The synchronous emergence of the structural transition and magnetism in Re-doped MoTe₂ under isotropic strain offers a great possibility to design novel and tunable spintronic devices.