Accelerated Discovery of the Valley-Polarized Quantum Anomalous Hall Effect in MXenes*

The topological phase preserved by spontaneous magnetization in non-centrosymmetric two-dimensional systems leads to valley-polarized quantum anomalous Hall (VP-QAH) insulators. Because of these strict criteria, the VP-QAH effect has been observed in a very few materials. We applied a high-throughput first-principles approach, wherein the magnetic and topological properties of inversion symmetry-broken 2D MXenes are screened, systematically. We find 14 MXenes having the out-of-plane ferromagnetic ground state in the presence of spin−orbit coupling. The nontrivial Berry curvature and chiral edge states confirm the VP-QAH effect in these MXenes. Furthermore, using basic elemental features, we have developed a machine-learning-based magnetic nodal line semimetal classification model and a regression model, which accurately predict both the nodal positions. Our study provides a robust platform to incorporate valley and topological physics, which would accelerate the search for promising VP-QAH materials.