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

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• The spin Hall effect (SHE) is vital for spintronics, generating spin currents via electrical current due to spin-orbit coupling.
• Achieving large SHEs, long spin transport, and magnetism simultaneously in one material is a significant challenge.
• Correlated magnetic materials typically exhibit weak SHEs.

Purpose of the Study:

• To demonstrate a giant intrinsic spin Hall effect coexisting with ferromagnetism in a single material.
• To explore the potential of moiré engineering for spintronics applications.
• To investigate the conditions required for simultaneous large SHE and magnetism.

Main Methods:

• Fabrication of AB-stacked MoTe2/WSe2 moiré bilayers.
• Direct magneto-optical imaging to observe spin accumulation.
• Application of moderate electrical currents (<1 A m⁻¹).
• Gate voltage modulation to study electronic properties.

Main Results:

• Demonstrated a giant intrinsic SHE coexisting with ferromagnetism in the moiré bilayers.
• Observed significant spin accumulation on transverse edges under moderate currents.
• Showcased long-range spin Hall transport and efficient non-local spin accumulation up to ~10 µm.
• Found the giant SHE is linked to the interaction-driven Chern insulating state and quantum anomalous Hall breakdown.

Conclusions:

• Moiré engineering of MoTe2/WSe2 bilayers enables simultaneous ferromagnetism and a giant spin Hall effect.
• This system offers a promising platform for spintronics due to long-range spin transport.
• The findings highlight the role of Berry curvature and electronic correlations in achieving advanced spintronic functionalities.