Polarity tuning of spin-orbit-induced spin splitting in two-dimensional transition metal dichalcogenides

Abstract

The established spin splitting in a monolayer (ML) of transition metal dichalcogenides (TMDs) induced by inversion symmetry breaking is dictated by mirror symmetry operations to exhibit the fully out-of-plane direction of spin polarization. Through first-principles density functional theory calculations, we show that polarity inducing mirror symmetry breaking leads to sizable spin splitting having in-plane spin polarization. These splittings are effectively controlled by tuning the polarity using biaxial strain. Furthermore, admixtures between the out-of-plane and in-plane spin-polarized states in the strained polar systems are identified, which are expected to influence the spin relaxation through the Dyakonov–Perel mechanism. Our study clarified that polarity plays an important role in controlling the spin splitting and spin relaxation in the TMD ML, which is useful for designing future spintronic devices.

Polarity Effect on the Electronic Structure of Molybdenum Dichalcogenides MoXY (X, Y = S, Se): A Computational Study Based on Density-Functional Theory

“…For example, in the equilibrium, we find that the α 1 value of the MoSSe for Γ -K direction is 0.669 eVÅ, which is smaller than that for Γ -M direction (1.224 eVÅ). The α 1 is comparable with that observed on the doped-PtSe 2 monolayer [12] and polar tungsten dichalcogenide monolayer [26,29]. In addition to α 1 , the system's anisotropic characteristic is also the result of the first and third-order Rashba parameters contribution, namely 3 1 and α 3 2 (see Table 3).…”

“…The SOC interaction was included self consistently in all calculations by using jdependent pseudopotentials [44]. The spin textures in the k-space were calculated using the spin density matrix of the spinor wave functions obtained from the DFT calculations that we applied recently to various 2D materials [10,12,16,26,29,[45][46][47][48].…”

“…This polar structure has already taken the attention since it has a great output on both optical and electrical properties [28]. The study of the electronic structure a TMDCs polar structure of WSSe reveals a shorter band gap rather than the nonpolar structure WS 2 , although both still obtain the identical substantial bandgap [29].…”

Rashba Effect on Buckled Square Lattice Ge and Sn chalcogenides (MX, M=Ge,Sn, X=O,S,Se,Te) using DFT method

“…However, due to the weak SOC, this material is not suitable for spinorbitronics [4][5][6]. Another example of 2D materials having hexagonal structure is coming from the transition metal dichalcogenides (TMDs) family [7].…”

Controlling the Superconducting Transition by Rotation of an Inversion Symmetry-Breaking Axis

“…In order to observe IP variations, we suggest growing a normal metal (N) with a cubic lattice structure at different angles compared to a transition metal dichalcogenide (TMDC) with IP inversion symmetry breaking [38], see Fig. 3(c).…”