Room‐Temperature 2D Topological Ferrimagnetic Semiconductors With Multiple Electronic Phase Transitions

ABSTRACT Integrating ferrimagnetic order and electronic topology in one two‐dimensional material has been highly expected to revolutionize the next‐generation high‐speed and ultralow‐loss information technology, but remains challenging. Here, via a half‐substitution strategy, the FeNb X 2 ( X = Se/Te) monolayer is proposed as the ferrimagnetic semiconductor with a nontrivial topological gap up to 107 meV and a high Chern number C = −2, exhibiting the high‐performance quantum anomalous Hall (QAH) effect. Moreover, both FeNbSe 2 and FeNbTe 2 belong to the Ising‐type ferrimagnet, holding a high Curie temperature of ∼500 K. The topological property is dominated by the band inversion of Nb‐d xy and Nb‐ orbitals near the spin‐polarized Dirac cone. Intriguingly, the unexpected electronic phase transitions among QAH, half‐metallic, and metallic states are observed in the present FeNb X 2 , and the phase diagrams are established. As a result, a spin field‐effect transistor with the functional FeNb X 2 monolayer is designed for switching on and off the QAH states. This work opens an avenue toward the realization and manipulation of exotic QAH effect in two‐dimensional ferrimagnetic systems, facilitating the emergent applications in spintronics and topotronics.