Magnetic Proximity-Induced Colossal Valley Splitting in WTe2 for Room Temperature Valleytronics

Abstract

Valleytronics, a burgeoning field of information technology, offers exciting possibilities for future information storage and computing. However, fully realizing its potential hinges on overcoming the inherent valley degeneracy in valleytronic materials. This study explores the possibility of lifting valley degeneracy in monolayer 2H-WTe₂ by using MnSe₂, a room-temperature ferromagnet, as a substrate. First-principles calculations show that a significant valley splitting of 236 meV can be achieved in the WTe₂/MnSe₂ heterostructure. This high level of splitting is attributed to the short-range magnetic proximity effect, mediated by interfacial orbital hybridization due to spatial charge redistribution and manifested by the induced magnetic moment on the W atom. The Berry curvature calculation confirms the broken time-reversal symmetry responsible for lifting the valley degeneracy, and the valley splitting can be further enhanced by modulating the interlayer distance. The Curie temperature of the MnSe₂ substrate is estimated to reach 457.57 K with 6% biaxial tensile strain, with the valley splitting retaining a value of 191 meV at this strain. The heterostructure also exhibits suitable band alignment for valley-polarized carrier transport and realization of the anomalous valley Hall effect, where the valley and spin indices of the carriers can be controlled by switching the magnetization direction of the MnSe₂ substrate. These phenomena, along with the strain tolerance of valley splitting, present a promising path toward room-temperature valleytronics, potentially revolutionizing future information technologies.