Gate-Tunable Reversible Rashba-Edelstein Effect in a Few-Layer Graphene/2H-TaS2 Heterostructure at Room Temperature

TL;DR

This paper demonstrates gate-tunable, reversible charge-to-spin conversion via the Rashba-Edelstein effect in a graphene/2H-TaS2 heterostructure at room temperature, revealing new control over spin polarization in nonmagnetic 2D materials.

Contribution

It reports the first observation of reversible electrical spin polarization control in a nonmagnetic layered heterostructure at room temperature.

Findings

Gate voltage reverses spin polarization direction.

Strong interface-induced Rashba interaction with a 70 meV spin-gap.

Supports design of low-power spin-logic circuits.

Abstract

We report the observation of current-induced spin polarization, the Rashba-Edelstein effect (REE), and its Onsager reciprocal phenomenon, the spin galvanic effect (SGE), in a few-layer graphene/2H-TaS2 heterostructure at room temperature. Spin-sensitive electrical measurements unveil full spin-polarization reversal by an applied gate voltage. The observed gate-tunable charge-to-spin conversion is explained by the ideal work function mismatch between 2H-TaS2 and graphene, which allows strong interface-induced Bychkov-Rashba interaction with a spin-gap reaching 70 meV, while keeping the Dirac nature of the spectrum intact across electron and hole sectors. The reversible electrical generation and control of the nonequilibrium spin polarization vector, not previously observed in a nonmagnetic material, are elegant manifestations of emergent 2D Dirac fermions with robust spin-helical structure. Our experimental findings, supported by first-principles relativistic electronic structure and transport calculations, demonstrate a route to design low-power spin-logic circuits from layered materials.