Abstract
By first-principles calculations, the magnetism of hole doped tin dichalcogenides SnX2 (X = S, Se) monolayers is systematically studied. It is found that a phase transition from nonmagnetic to ferromagnetic ground state appears once above the critical hole density (~1014 cm−2). The spin magnetic moment can maintain a magnitude of 1.0 μB/hole with excellent stability of ferromagnetic state. Furthermore, we demonstrate that strain is very useful to modulate the DOS near the valence band, resulting in the reduction of the critical hole density to ~1013 cm−2 when the strain reaches 4% (6%) in SnS2 (SnSe2), which can be realized in common field effect transistors. Moreover, the phonon dispersion calculations for the strained SnX2 monolayers indicate that they can keep the dynamical stability under the hole doping. Therefore, the strain tunable magnetic transition in hole doped tin dichalcogenides indicates their potential promising applications in spintronic devices.
Highlights
Thick two-dimensional (2D) layered materials are currently one of most research interests for their promising applications in electronics, optoelectronics and spintronics[1,2,3,4]
It is worth noting that some 2D semiconductors exist unusual band structures, one of which is the Mexican hat dispersions, such as gallium or indium monochalcogenides, often resulting in van Hove singularities (VHSs) divergence in the DOS24,25
To examine the dynamical stability of SnX2 monolayers with doping, the phonon dispersion was calculated by density functional perturbation theory in Vienna Ab Initio Simulation Package (VASP)
Summary
To study the electronic and magnetic properties of the SnX2 monolayers, density functional theory (DFT) calculations were performed using the Projector-Augmented Wave (PAW) pseudopotential implementation of the Vienna Ab Initio Simulation Package (VASP)[35,36,37]. Electron exchange and correlation effects were described by the generalized gradient approximation (GGA) functional of Perdew-Burke-Ernzerhofer (PBE) formula[38]. The energy cutoff for the plane-wave basis was set as 550 eV on the 11 × 11 × 1 Monkhorst-Pack k-point grid for all simulations. The convergence threshold was 1 × 10−5 eV for the electronic self-consistent field iterations. To examine the dynamical stability of SnX2 monolayers with doping, the phonon dispersion was calculated by density functional perturbation theory in VASP
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