Robust Quantum Anomalous Hall Effect in Ferromagnetic Janus Cr 3 X 2 Y 2 (X, Y = S, Se, Te) Monolayers: Implications for Dissipationless Quantum Computing Devices

The realization of the quantum anomalous Hall (QAH) effect relies on the synergy of ferromagnetic ordering, spin–orbit coupling (SOC), and a global topological band gap in materials. Via first-principles calculations, we predict a family of stable QAH insulators: Cr 3 X 2 Y 2 (X, Y = S, Se, Te) monolayers. All systems exhibit a stable ferromagnetic ground state with Curie temperatures ranging from 150 to 200 K. Without SOC, the three Cr 3 X 2 Y 2 monolayers show half metallicity with linear band crossings at the K point. Upon including SOC, sizable topological band gaps open at the K point, accompanied by a nonzero Chern number C = −1. Furthermore, the electronic and magnetic properties of all studied systems are sensitive to external strains, allowing for tunable transitions between QAH insulating, AFM, and QAH metallic phases. These findings uncover the nontrivial topological nature of Cr 3 X 2 Y 2 monolayers, establishing them as promising candidates for topological quantum devices.