Tunable room-temperature spin galvanic and spin Hall effects in van der Waals heterostructures

TL;DR

This paper demonstrates tunable, high-efficiency spin-to-charge conversion at room temperature in graphene/WS2 heterostructures, controlled by electrostatic gating, enabling advances in spintronics without magnetic materials.

Contribution

It reveals a novel, electrically tunable spin galvanic and spin Hall effect in van der Waals heterostructures at room temperature, with efficiencies comparable to the best reported.

Findings

Enhanced room-temperature spin-to-charge conversion in graphene/WS2.

Electrostatic gating controls the magnitude and sign of conversion.

Conversion efficiencies peak near charge neutrality, rivaling top efficiencies.

Abstract

Spin-orbit coupling stands as a powerful tool to interconvert charge and spin currents and to manipulate the magnetization of magnetic materials through the spin torque phenomena. However, despite the diversity of existing bulk materials and the recent advent of interfacial and low-dimensional effects, control of the interconvertion at room-temperature remains elusive. Here, we unequivocally demonstrate strongly enhanced room-temperature spin-to-charge (StC) conversion in graphene driven by the proximity of a semiconducting transition metal dichalcogenide(WS2). By performing spin precession experiments in properly designed Hall bars, we separate the contributions of the spin Hall and the spin galvanic effects. Remarkably, their corresponding conversion effiencies can be tailored by electrostatic gating in magnitude and sign, peaking nearby the charge neutrality point with a magnitude that is comparable to the largest efficiencies reported to date. Such an unprecedented electric-field tunability provides a new building block for spin generation free from magnetic materials and for ultra-compact magnetic memory technologies.