Magnetism in disjoint/non-disjoint composite bands

Non-bonding degenerate systems with disjoint/non-disjoint composite bands are suggested. In these systems, one of the non-bonding bands is disjoint, and another is non-disjoint type. Whereas the Wannier functions in the former bands span no common atoms, the Wannier functions in the latter bands span common atoms. Regardless of the disjoint bands, these systems are predicted to be ferromagnetic due to non-trivial exchange interactions in the non-disjoint bands. The ferromagnetic interactions are supported by DFT calculations.