Giant spin Hall effect in AB-stacked MoTe2/WSe2 bilayers

TL;DR

This paper reports the discovery of a giant intrinsic spin Hall effect in AB-stacked MoTe2/WSe2 bilayers, enabled by moiré engineering, with potential applications in spintronics.

Contribution

The study demonstrates a giant intrinsic spin Hall effect in moiré bilayers, linking it to Berry curvature engineering and quantum anomalous Hall states.

Findings

Giant spin Hall effect observed via magneto optical imaging

Long-range spin transport over about 10 micrometers

Giant SHE occurs near Chern insulating state and after quantum anomalous Hall breakdown

Abstract

The spin Hall effect (SHE), in which electrical current generates transverse spin current, plays an important role in spintronics for the generation and manipulation of spin-polarized electrons. The phenomenon originates from spin-orbit coupling. In general, stronger spin-orbit coupling favors larger SHEs but shorter spin relaxation times and diffusion lengths. To achieve both large SHEs and long-range spin transport in a single material has remained a challenge. Here we demonstrate a giant intrinsic SHE in AB-stacked MoTe2/WSe2 moir\'e bilayers by direct magneto optical imaging. Under moderate electrical currents with density < 1 A/m, we observe spin accumulation on transverse sample edges that nearly saturates the spin density. We also demonstrate long-range spin Hall transport and efficient non-local spin accumulation limited only by the device size (about 10 um). The gate dependence shows that the giant SHE occurs only near the Chern insulating state, and at low temperatures, it emerges after the quantum anomalous Hall breakdown. Our results demonstrate moir\'e engineering of Berry curvature and large SHEs for potential spintronics applications.