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

Abstract

Manipulation of the valley degree of freedom provides a new path for quantum information technology, but the real intrinsic large valley-polarization materials are few reported up to date. Here, we perform first-principles calculations to predict a class of 2H-phase single layer (SL) materials LuX 2 (X=Cl, Br, I) to be ideal candidates. SL-LuX 2 are ferrovalley materials with a giant valley-polarization of 55~148 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 89~124K, with a sizable magnetic anisotropy with out-of-plane direction. Remarkably, the anomalous valley Hall effect (AVHE) can be controlled in SL-LuX 2 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 experiment of valleytronics and the subsequent application.

Design of sign-reversible Berry phase effect in 2D magneto-valley material

“…Furthermore, considering the perspective of potential applications in valleytronics, except for AVHE, the exploration for magneto-valley materials with valley-related multiple Hall effect (MHE) is of significant importance, which can enrich the valley-related physics and emerging quantum states of matter. One exotic valley-related multiple Hall effect is the quantum anomalous valley Hall effect (QAVHE), [36][37][38][39][40] which possesses the interplay between valley and band topology and combines the valley index and quantum anomalous Hall effect (QAHE), [36] making it possible to realize high-performance quantum devices and thus raising an intensive interest in materials science. However, the realization of QAVHE [37] relies on the combination of SOC, band topology and magnetic ordering, which pose a great challenge for the research on potential high-performance valley-controllable quantum computational devices in 2D materials.…”