Efficient Spin Transfer in WTe2/Fe3GeTe2 van der Waals Heterostructure Enabled by Direct Interlayer p-Orbital Hybridization

TL;DR

This study reveals that direct p-orbital hybridization at the WTe2/Fe3GeTe2 interface enhances interlayer spin transfer, explaining high spin transparency and efficiency in van der Waals heterostructures, with potential for device optimization.

Contribution

It uncovers the microscopic mechanism of efficient spin transfer via interlayer p-orbital hybridization in WTe2/Fe3GeTe2 heterostructures, advancing spintronic device design.

Findings

Interlayer p-orbital hybridization lowers the potential barrier.

Enhanced spin-polarized electronic structure facilitates spin transfer.

Gate voltage can further improve spin-orbit torque efficiency.

Abstract

Recent experiments have demonstrated efficient spin transfer across layers in the van der Waals heterostructure composed of WTe2 and Fe3GeTe2, signaling a potential breakthrough in developing all-van der Waals spin-orbit torque devices. However, the reasons behind the unusually high interlayer spin transparency observed, despite the weak van der Waals interactions between layers, remain unclear. In this study, we employ density functional theory and the non-equilibrium Green's function method to explore this phenomenon. We find that the efficient cross-layer spin transfer arises from direct hybridization of p-orbitals between tellurium atoms at the interface. This interlayer orbital hybridization lowers the electronic potential barrier and significantly modifies the spin-polarized electronic structure of Fe3GeTe2. Consequently, an effective channel for spin-polarized transport is established between WTe2 and Fe3GeTe2, leading to high interlayer spin transparency. Combining this enhanced spin transparency with the large spin Hall angle of WTe2 explains the high spin-orbit torque efficiency observed experimentally. Furthermore, we predict that applying a gate voltage can further increase this efficiency. Our findings offer a pathway for designing high-performance, all-van der Waals spin-orbit torque devices.