High-throughput discovery of topological and magnetic phases in Heuslerenes

We report a first-principles, high-throughput search of X2YZ “Heuslerenes” generated by symmetry-guided exfoliation of their bulk Heusler parents. Calculated elastic tensors satisfy the 2D Born criteria, indicating mechanical stability as freestanding crystals. A deep-learning pipeline that embeds, classifies, and clusters the electronic band structures reveals three functionally distinct subsets: (i) 32 small-gap semiconductors with linear-band features alongside several half-metals exhibiting 100% spin polarization at the Fermi level, (ii) 98 compounds with noncollinear magnetic moments >1μB per formula unit, and (iii) 15 systems with ultra-low work functions, Φ < 3.0 eV, promising for spin filters, magnetoelectronics, and vacuum emitters. Topological diagnostics, parity eigenvalues, and Berry-curvature-based invariants reveal a diversity of nontrivial phases, including time-reversal invariant Z2 topological insulators and time-reversal symmetry breaking weakly magnetic Chern insulators; the latter include Rh2HfMg, which exhibits a large intrinsic anomalous Hall conductivity, σxy ≈ 285 S cm−1. Analysis of exciton absorption spectra within the framework of many-body perturbation theory and Bethe–Salpeter equations reveals large exciton binding energies, Eb > 2.3 eV, and possible excitonic insulator phases in other Rh-based Heuslerenes. Collectively, these results position Heuslerenes as a multifunctional 2D platform uniting robust magnetism, symmetry-protected topological transport, and excitonic tunability. More broadly, our symmetry-aware structure generation coupled with automated electronic, magnetic, and topological characterization defines an efficient workflow for designing quantum materials for next-generation spintronics and topological devices.