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Abstract:
Using density functional theory based calculations, we show that the
correlated mixed-valent compound SmO is a three-dimensional strongly
topological semimetal as a result of a 4f -5d band inversion at the X
point. The [001] surface Bloch spectral density reveals two weakly
interacting Dirac cones that are quasidegenerate at the (M) over bar
point and another single Dirac cone at the (Gamma) over bar point. We
also show that the topological nontriviality in SmO is very robust and
prevails for a wide range of lattice parameters, making it an ideal
candidate to investigate topological nontrivial correlated flat bands in
thin-film form. Moreover, the electron filling is tunable by strain. In
addition, we find conditions for which the inversion is of the 4f -6s
type, making SmO to be a rather unique system. The similarities of the
crystal symmetry and the lattice constant of SmO to the well studied
ferromagnetic semiconductor EuO, makes SmO/EuO thin film interfaces an
excellent contender towards realizing the quantum anomalous Hall effect
in a strongly correlated electron system.
