Metal-free magnetism in 2D frameworks

Metal-free magnetism in organic 2D frameworks has garnered significant interest for its potential in organic spintronics and quantum technologies. [1-2] However, achieving stable spin-polarization and controlling magnetic interactions in organic materials remains significantly challenging due to weak electron correlations. In this presentation, I will show that electron correlation and magnetic interactions in organic 2D frameworks can be tuned to induce spontaneous spin-polarization. Using nanographenes with stable radicals as spin units, we designed a series of topological 2D frameworks with a honeycomb lattice. [3-5] These frameworks exhibit unique electronic properties, including a Dirac point flanked by twin flat bands, consistent with a px-py tight-binding model. At half-filling, where the Fermi level intersects the Dirac point, the systems behave as antiferromagnetic Mott-Hubbard insulators. By tuning the Fermi level, we achieve metal-free ferromagnetism and potential half-metallic behavior. Notably, these frameworks display robust ferromagnetic interactions of approximately 60 meV, surpassing predictions from Lieb’s theorem.