  In this work, we investigate models for bulk, bi- and multilayers containing
half-metallic ferromagnets (HMFs), at zero and at finite temperature, in order
to elucidate the effects of strong electronic correlations on the spectral
properties (density of states). Our focus is on the evolution of the
finite-temperature many-body induced tails in the half-metallic gap. To this
end, the dynamical mean-field theory (DMFT) is employed. For the bulk, a Bethe
lattice model is solved using a matrix product states based impurity solver at
zero temperature and a continuous-time quantum Monte Carlo (CT-QMC) solver at
finite temperature. We demonstrate numerically, in agreement with the
analytical result, that the tails vanish at the Fermi level at zero
temperature. In order to study multilayers, taken to be square lattices within
the layers, we use the real-space DMFT extension with the CT-QMC impurity
solver. For bilayers formed by the HMF with a band or correlated insulator, we
find that charge fluctuations between the layers enhance the finite temperature
tails. In addition, in the presence of inter-layer hopping, a coherent
quasiparticle peak forms in the otherwise correlated insulator. In the
multilayer heterostructure setup, we find that by suitably choosing the model
parameters, the tails at the HMF/Mott insulator interface can be reduced
significantly, and that a high spin polarization is conceivable, even in the
presence of long-ranged electrostatic interactions.
