Predicted septuple-atomic-layer Janus $\mathrm{MSiGe}{\mathrm{N}}_4$ (M=Mo and W) monolayers with Rashba spin splitting and high electron carrier mobilities

Abstract

Janus two-dimensional (2D) materials have attracted much attention due to possessing unique properties caused by their out-of-plane asymmetry, which have been achieved in many 2D families. In this work, the Janus monolayers are predicted in new 2D $\mathrm{M}{\mathrm{A}}_2{\mathrm{Z}}_4$ family by means of first-principles calculations, $\mathrm{MoS}{\mathrm{i}}_2{\mathrm{N}}_4$ and $\mathrm{WS}{\mathrm{i}}_2{\mathrm{N}}_4$ of which have been synthesized in experiment(\textcolor[rgb]{0.00,0.00,1.00}{Science 369, 670-674 (2020)}). The predicted $\mathrm{MSiGe}{\mathrm{N}}_4$ (M=Mo and W) monolayers exhibit dynamic, thermodynamical and mechanical stability, and they are indirect band-gap semiconductors. The inclusion of spin-orbit coupling (SOC) gives rise to the Rashba-type spin splitting, which is observed in the valence bands, being different from common conduction bands. Calculated results show valley polarization at the edge of the conduction bands due to SOC together with inversion symmetry breaking. It is found that $\mathrm{MSiGe}{\mathrm{N}}_4$ (M=Mo and W) monolayers have high electron mobilities. Both in-plane and much weak out-of-plane piezoelectric polarizations can be observed, when a uniaxial strain in the basal plane is applied. The values of piezoelectric strain coefficient $d_{11}$ of the Janus $\mathrm{MSiGe}{\mathrm{N}}_4$ (M=Mo and W) monolayers fall between those of the $\mathrm{MS}{\mathrm{i}}_2{\mathrm{N}}_4$ (M=Mo and W) and $\mathrm{MG}{\mathrm{e}}_2{\mathrm{N}}_4$ (M=Mo and W) monolayers, as expected. It is proved that strain can tune the positions of valence band maximum (VBM) and conduction band minimum (CBM), and enhance the the strength of conduction bands convergence caused by compressive strain. It is also found that tensile biaxial strain can enhance $d_{11}$ of $\mathrm{MSiGe}{\mathrm{N}}_4$ (M=Mo and W) monolayers, and the compressive strain can improve the $d_{31}$ (absolute values).

10 pages, 11 figures

References in corpus (19)

• Electric Field Effect in Atomically Thin Carbon Films
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Intrinsic magnetic topological insulators in van der Waals layered MnBi${}_2$Te${}_4$-family materials
• Systematic treatment of displacements, strains and electric fields in density-functional perturbation theory
• Elastic properties of hydrogenated graphene
• Giant Piezoelectricity in Monolayer Group IV Monochalcogenides: SnSe, SnS, GeSe and GeS
• Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2
• Ab-Initio Simulations of Deformation Potentials and Electron Mobility in Chemically Modified Graphene and two-dimensional hexagonal Boron-Nitride
• PyProcar: A Python library for electronic structure pre/post-processing
• Flexural phonons in free-standing graphene
• Physically founded phonon dispersions of few-layer materials, and the case of borophene
• Predicted Janus SnSSe monolayer: a comprehensive first-principle study
• Giant tunable Rashba spin splitting in two-dimensional BiSb monolayer and BiSb/AlN heterostructures
• Intrinsic piezoelectricity in monolayer $\mathrm{XS}{\mathrm{i}}_2{\mathrm{N}}_4$ (X=Ti, Zr, Hf, Cr, Mo and W)
• Coexistence of intrinsic piezoelectricity and ferromagnetism induced by small biaxial strain in septuple-atomic-layer $\mathrm{VS}{\mathrm{i}}_2{\mathrm{P}}_4$
• Biaxial strain tuned electronic structures and power factor in Janus Transition Metal Dichalchogenide monolayers
• Biaxial strain enhanced piezoelectric properties in monolayer g-${\mathrm{C}}_3{\mathrm{N}}_4$

Cited by in corpus (9)

• High intrinsic lattice thermal conductivity in monolayer MoSi${}_2$N${}_4$
• Strain effects on topological and valley properties of Janus monolayer $\mathrm{VSiGe}{\mathrm{N}}_4$
• MoSi${}_2$N${}_4$-like crystals -- the new family of two-dimensional materials
• Intrinsic ferromagnetism and restrictive thermodynamic stability in MA${}_2$N${}_4$ and Janus VSiGeN${}_4$ monolayers
• Tuning transport coefficients of monolayer $\mathrm{MoS}{\mathrm{i}}_2{\mathrm{N}}_4$ with biaxial strain
• Rashba dominated spin-splitting in the bulk ferroelectric oxide perovskite KIO3
• Manipulation of valley and spin properties in two-dimensional Janus WSiGeZ${}_4$ (Z=N,P, As) through symmetry control
• Stable Ferromagnetism and High Curie Temperature in VGe${}_2$N${}_4$
• Exploration of the two-dimensional Ising magnetic materials in the triangular prismatic crystal field