Unidirectional Spin–Orbit Interaction Induced by the Line Defect in Monolayer Transition Metal Dichalcogenides for High-Performance Devices

Abstract

Spin–orbit (SO) interaction is an indispensable element in the field of spintronics for effectively manipulating the spin of carriers. However, in crystalline solids, the momentum-dependent SO effective magnetic field generally results in spin randomization by a process known as the Dyakonov–Perel spin relaxation, leading to the loss of spin information. To overcome this obstacle, the persistent spin helix (PSH) state with a unidirectional SO field was proposed but difficult to achieve in real materials. Here, on the basis of first-principles calculations and tight-binding model analysis, we report for the first time a unidirectional SO field in monolayer transition metal dichalcogenides (TMDs, MX2, M = Mo, W; and X = S, Se) induced by two parallel chalcogen vacancy lines. By changing the relative positions of the two vacancy lines, the direction of the SO field can be tuned from x to y . Moreover, using k · p perturbation theory and group theory analysis, we demonstrate that the emerging unidirectional SO field is subject to both the structural symmetry and 1D nature of such defects engineered in 2D TMDs. In particular, through transport calculations, we confirm that the predicted SO states carry highly coherent spin current. Our findings shed new light on creating PSH states for high-performance spintronic devices.

Enhanced Berry Curvature Dipole and Persistent Spin Texture in the Bi(110) Monolayer

“…Depending on the field direction, a variety of SOC Hamiltonians are possible. 7,8,15,16 The conventional Rashba SOC effect has an out-of-plane electric field E = E z z, leading to an in-plane helical spin texture. However, the polarization in the puckered Bi(110) monolayer is in-plane to produce an in-plane electric field E = E x x.…”

“…11 The BCD-induced nonlinear Hall effect has been proposed in several 2D materials, such as single layer transition metal dichalcoginides 12,13 and a SnTe monolayer, 14 and confirmed experimentally in a WTe 2 monolayer. 2,3 The PST has been reported in a few 1D defetcs 7,8 and 2D systems of group-IV monochalcogenides. 15,16 Although these two properties have been observed and discussed in different materials, they may be fundamentally related, since both require inversion asymmetry and strong SOC.…”

Probing Proximity‐Tailored High Spin–Orbit Coupling in 2D Materials

“…Molybdenum disulfide (MoS 2 ) is a layered transition metal dichalcogenide (TMD) with a high spin–orbit coupling (SOC) and its monolayer has direct bandgap absorption in the visible light (1.9 eV) with broken inversion symmetry and large valley splitting. [ 1–5 ] These properties make monolayer MoS 2 (MS) a unique platform to study light–matter interactions using Spin Hall effect of light (SHEL). In general, MS is non‐magnetic with weak ferromagnetism reported for free standing MS due to the edge states.…”

Discovery Principles and Materials for Symmetry-Protected Persistent Spin Textures with Long Spin Lifetimes

“…Although the effects of the spin deviations can be theoretically eliminated in 1D line defects 38 and 2D monolayers, 39 the spin lifetime may not be significantly enhanced. 40 Moreover, these methods are extreme and limited to unique boundary conditions of a few materials.…”