Quantum anomalous Hall effect with high Chern number in two dimensional ferromagnets Ti2TeSO

Abstract

Two-dimensional Chern insulators have emerged as crucial platforms for the realization of the quantum anomalous Hall effect, and as such have attracted significant interest in spintronics and topological quantum physics due to their unique coexistence of spontaneous magnetization and nontrivial topological characteristics. Nonetheless, substantial challenges persist in such systems, encompassing spin entanglement and the possession of only one edge state (Chern number C=1), which significantly hinder their practical applications. Herein, we propose a novel two-dimensional ferromagnetic half-semi-Weyl-metal, monolayer Ti2TeSO, that exhibits exceptional electronic properties. Its majority spin channel possesses only a pair of symmetry-protected Weyl points at the Fermi level, while the states of minority one locate far away from the Fermi level. When spin-orbit coupling is included, a substantial band gap of ~ 92.8 meV is induced at the Weyl points. Remarkably, the emergence of dual dissipationless chiral edge channels and a quantized Hall conductivity plateau at 2e2/h collectively establish monolayer Ti2TeSO as a high-Chern-number insulator with C=2. Furthermore, it is demonstrated that valley polarization can be achieved and controlled through the application of strain and the manipulation of the direction of magnetization. The first-principles calculations, in conjunction with Monte Carlo simulations, yield a Curie temperature of 161 K for monolayer Ti2TeSO, thereby indicating the plausibility of coexistence of valley polarization and topological states at elevated temperatures. These findings could provide a foundation for the development of multi-channels dissipationless transport devices and nonvolatile multistate memory architectures.

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