Magnetic Proximity Induced Giant Enhancement of Valley Polarization and Zeeman Splitting in WS<sub>2</sub>/Fe<sub>3</sub>GaTe<sub>2</sub> Heterostructures.

Ali, Wajid; Yang, Liuli; Xie, Yunfei; Song, Hao; Huang, Ming; Rehman, Sajid Ur; Li, Ziwei; Muhammad, Zahir et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Substrate engineering offers a powerful approach to tailoring quasiparticle interactions in two-dimensional (2D) materials for valley-quantum devices. Here, a significantly enhanced valley polarization of 67% has been observed in a WS<sub>2</sub> monolayer on a thin Fe<sub>3</sub>GaTe<sub>2</sub> (FGT) layer under far-off resonant excitation at 10 K, which is much higher than that of 16% detected from WS<sub>2</sub> monolayer. This enhancement is attributed to the magnetic proximity effect, which leads to a shorter exciton lifetime in the heterostructure without affecting the valley scattering time. The temperature dependence of valley polarization strongly correlates with the thermomagnetic behavior of the FGT film, suggesting a strong exciton-magnon coupling. Additionally, we observe a valley Zeeman splitting of -5 meV, corresponding to an effective Landé <i>g</i>-factor of -66.03, supported by first-principles calculations. These findings underscore the importance of substrate engineering in modulating intrinsic valley carriers of ultrathin 2D materials, opening new avenues for valleytronic devices.