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Unidirectional Spin–Orbit Interaction Induced by the Line Defect in Monolayer Transition Metal Dichalcogenides for High-Performance Devices
journal contribution
posted on 2019-08-13, 20:30 authored by Xiaoyin Li, Shunhong Zhang, Huaqing Huang, Lin Hu, Feng Liu, Qian WangSpin–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.