Fen=4,5βGeTe2β exhibits quasi-two-dimensional properties as a
promising candidate for a near-room-temperature ferromagnet, which has
attracted great interest. In this work, we notice that the crystal lattice of
Fen=4,5βGeTe2β can be approximately considered to be stacked by
three bipartite crystal lattices. By combining the model Hamiltonians of
bipartite crystal lattices and first-principles calculations, we investigate
the electronic structure and the magnetism of Fen=4,5βGeTe2β. We
conclude that flat bands near the Fermi level originate from the bipartite
crystal lattices and that these flat bands are expected to lead to the
itinerant ferromagnetism in Fen=4,5βGeTe2β. Interestingly, we also
find that the magnetic moment of the Fe5 atom in Fe5βGeTe2β is
distinct from the other Fe atoms and is sensitive with the Coulomb interaction
U and external pressure. These findings may be helpful to understand the
exotic magnetic behavior of Fen=4,5βGeTe2β.Comment: 9 pages, 8 figure