Single-layer intrinsic 2H-phase LuX₂ (X = Cl, Br, I) with large valley polarization and anomalous valley Hall effect

Manipulation of the valley degree of freedom provides a new path for quantum information technology, but the real intrinsic large valley-polarization materials are rarely reported up to date. Here, we perform first-principles calculations to predict a class of 2H-phase single layer (SL) materials LuX₂ (X = Cl, Br, I) to be ideal candidates. SL-LuX₂ are ferrovalley materials with a giant valley-polarization of 55 meV–148 meV as a result of its large spin–orbital coupling (SOC) and intrinsic ferromagnetism (FM). The magnetic transition temperatures of SL-LuI₂ and SL-LuCl₂ are estimated to be 89 K–124 K, with a sizable magnetic anisotropy at out-of-plane direction. Remarkably, the anomalous valley Hall effect (AVHE) can be controlled in SL-LuX₂ when an external electric field is applied. Moreover, the intrinsic valley-polarization of SL-LuI₂ is highly robust for biaxial strain. These findings provide a promising ferrovalley material system for the experimentation of valleytronics and subsequent applications.