Large valley polarization and high Curie temperature in single layer XI<sub>2</sub> (X = Sc, Y)
Mengxian Lan, Ying Li, Shiqian Qiao, Tian Huang, Sai Ma, Feng Ding, Hong Wu, Feng Li, Yong Pu
Abstract
Abstract Ferrovalley materials with spontaneous valley polarization are the key to valleytronics applications. Therefore, it is important to find materials with relatively large valley polarization. In this work, we theoretically designed two novel two-dimensional ferrovalley materials namely XI 2 (X = Sc, Y), which have both high Curie temperature and large valley polarization. The Curie temperature of monolayer ScI 2 and YI 2 are 138 K and 58 K, the large valley polarization of 97 meV and 108 meV are also predicted in monolayer ScI 2 and YI 2 . The anomalous valley Hall effect is also proposed based on the valley contrasting Berry curvature. In addition, strain engineering can effectively modulate the valley polarization and Curie temperature of monolayer XI 2 (X = Sc, Y). The Curie temperature of ScI 2 increases with increasing strain, and the valley polarization of YI 2 increases with increasing strain. Our findings suggest that monolayer XI 2 (X = Sc, Y) is a promising material for valleytronics.