Enhancement of spin Hall angle by an order of magnitude via Cu intercalation in MoS2/Co-Fe-B heterostructures

Abstract

Transition-metal dichalcogenides (TMDs) are a novel class of quantum materials with significant potential in spintronics, optoelectronics, valleytronics, and optovalleytronics. TMDs exhibit strong spin-orbit coupling, enabling efficient spin-charge interconversion, which makes them ideal candidates for spin-orbit torque-driven spintronic devices. In this study, we have investigated the spin-to-charge conversion through ferromagnetic resonance in Mo⁢S2/Cu/Co-Fe-B heterostructures with varying Cu spacer thicknesses. The conversion efficiency, quantified by the spin Hall angle, has been enhanced by an order of magnitude due to Cu intercalation. Magneto-optic Kerr effect microscopy has confirmed that Cu does not significantly modify the magnetic domains, indicating its effectiveness in decoupling Mo⁢S2 from Co-Fe-B. This decoupling preserves the spin-orbit coupling (SOC) of Mo⁢S2 by mitigating the exchange interaction with Co-Fe-B, as proximity to localized magnetization can alter the electronic structure and the SOC. First-principles calculations have revealed that Cu intercalation notably enhances the spin Berry curvature and spin Hall conductivity, contributing to the increased spin Hall angle. This study demonstrates that interface engineering of ferromagnet–TMD-based heterostructures can achieve higher spin-to-charge conversion efficiencies, paving the way for advancements in spintronic applications.