Charge-spin conversion in layered semimetal TaTe2 and spin injection in van der Waals heterostructures

Abstract

A spin-polarized current source using nonmagnetic layered materials is promising for next-generation allelectrical spintronic science and technology. Here we electrically created spin polarization in a layered semimetal TaTe 2 via the charge-spin conversion process. Using a hybrid device of TaTe 2 in a van der Waals heterostructure with graphene, the spin polarization in TaTe 2 is efficiently injected and detected by nonlocal spin-switch, Hanle spin precession, and inverse spin Hall effect measurements. Systematic experiments at different bias currents and gate voltages in a vertical geometry prove the TaTe 2 as a nonmagnetic spin source at room temperature. These findings demonstrate the possibility of making an all-electrical spintronic device in a two-dimensional van der Waals heterostructure, which can be essential building blocks in energy-efficient spin-orbit technology.

All-electrical creation and control of spin-galvanic signal in graphene and molybdenum ditelluride heterostructures at room temperature

“…Specifically, the SOI is the origin of fascinating effects like current-induced transverse spin polarization in non-magnetic materials, known as spin Hall effect (SHE) in bulk, Rashba-Edelstein effect (REE) at the heterostructure interfaces, and spin-momentum locking (SML) in topological materials 5 . Recent experiments utilizing the charge-to-spin conversion (CSC) and its inverse effects have been performed on metallic multilayers 6 , semiconductors 2 , oxide heterostructures 7,8 , two-dimensional (2D) materials 9,10 , van der Waals (vdW) heterostructures with graphene (Gr) [11][12][13][14][15][16][17] , and the topological insulators 18,19 . Such SOI-induced charge-spin conversion features are promising for all-electrical spinorbit torque-based technology [1][2][3][4] .…”

Spin-Orbit Torques in Transition Metal Dichalcogenide/Ferromagnet Heterostructures

“…In this mini-review, we give an overview of the recent progress on SOTs in TMD/FM heterostructures. Materials with high charge-tospin conversion efficiencies, such as WTe 2 and TaTe 2 (Safeer et al, 2019;Zhao et al, 2020;Hoque et al, 2020), are often considered as good candidates for large SOT efficiencies. However, large chargeto-spin conversion efficiencies are no guarantee for large SOT efficiencies, as SOTs are often an emergent phenomenon, depending on proximity effects (spin-orbit coupling and magnetic exchange), wavefunction overlap, and interface spin transparency (spin mixing conductance) as well.…”

Berry curvature-induced local spin polarisation in gated graphene/WTe$_2$ heterostructures

“…Complementing interface design with external control via gate fields [6], the electronic properties can be manipulated on-demand, enabling for example switchable topology or spintronic functionality. In particular, graphene as a spin transport channel com-bined with a strong SOC 2D material as spin generator enables a gate-tunable spin-charge interconversion [1,2], as has been demonstrated for vdW heterostructures incorporating a 3D topological insulator [11], a trivial or topological 2D semimetal [8,12,13], or a 2D semiconductor [7,9,10,14,15]. The electrically detected spin-signal can even persist up to room temperature, which is highly desirable for applications [9,[11][12][13][14][15][16].…”

“…Heterostructures combining graphene with a strongly spin-orbit coupled twodimensional (2D) material enable such functionality by design [3][4][5][6]. Electric spin valve experiments have provided so far global information on such devices [7][8][9][10][11][12][13][14][15][16], while leaving the local interplay between symmetry breaking, charge flow across the heterointerface and aspects of topology unexplored. Here, we utilize magnetooptical Kerr microscopy to resolve the gatetunable, local current-induced spin polarisation in graphene/WTe 2 van der Waals (vdW) heterostructures.…”