Spin-Valley Locking in 2H-TaS2 and Its Co-Intercalated Counterpart: Roles of Surface Domains and Co Intercalation

TL;DR

This study uses spatially resolved spin-ARPES to demonstrate robust spin-valley locking in 2H-TaS2 and its Co-intercalated form, revealing surface domain effects and the impact of interlayer hybridization on spin textures.

Contribution

It provides the first spatially resolved spin-ARPES analysis showing how surface domains and Co intercalation influence spin-valley locking in layered TMDs.

Findings

Robust spin-valley locking observed in both compounds

Co intercalation enhances interlayer hybridization and magnetism

Surface domains cause reversal of out-of-plane spin polarization

Abstract

Tuning and probing spin-valley coupling is key to understanding correlated ground states in 2$\it{H}$-TaS$_2$. Its magnetically intercalated analogue, Co$_{1/3}$TaS$_2$, introduces additional degrees of freedom, including modified interlayer coupling and magnetism, to modulate spin-valley physics. Surface-sensitive probes like ARPES are essential for accessing surface spin texture, yet previous studies on 2$\it{H}$-TMDs have reported conflicting results regarding spin-polarized bands, leaving open whether these discrepancies are intrinsic or extrinsic. Here we performed spatially resolved spin-ARPES measurements on 2$\it{H}$-TaS$_2$ and Co$_{1/3}$TaS$_2$. Our results reveal robust spin-valley locking on both compounds. Importantly, Co intercalation enhances interlayer hybridization and introduces magnetism while preserving the TaS$_2$-derived spin texture. We further observe a spatial reversal of the out-of-plane spin polarization, which we attribute to different surface domains. This effect complicates quantifying spin textures and may underlie prior inconsistent observations. Our findings provide microscopic insight into how interlayer interactions and surface domains together govern spin-valley phenomena in layered TMDs.