Interaction Instabilities in Organic Filling-Enforced Semimetals

The identification of experimentally viable nodal semimetals is a crucial step towards the advancement of topological condensed matter physics. Recent efforts have exploited symmetry and electron-counting considerations to narrow this search, focusing on so-called "filling-enforced" (fe-) semimetals. Examining thousands of DFT calculations of previously synthesized organic crystals tabulated in the Organic Materials Database (OMDB) http://omdb.diracmaterials.org, we find over 100 candidate fe-semimetals, and observe that all of them instead develop spontaneous magnetization, a result consistent with available experimental literature. We employ machine-learning to explore this relationship, finding that among thousands of charge-counting- and crystalline-symmetry-based features, minimal insulating filling is the leading predictor of magnetization in the OMDB. We conclude by also discussing possible antiferromagnetic, Mott insulating, and superconducting phases. The band structures and results presented in this talk are freely accessible at http://supmagnetic.diracmaterials.org/.