https://doi.org/10.1007/s100510050722
Dynamical mean-field study of the Mott transition in thin films
Institut für Physik,
Humboldt-Universität zu Berlin,
Invalidenstrasse 110, 10115 Berlin,
Germany
Received:
19
August
1998
Published online: 15 April 1999
The correlation-driven transition from a paramagnetic metal to
a paramagnetic Mott-Hubbard insulator is studied within
the half-filled Hubbard model for a thin-film geometry. We consider
simple-cubic films with different low-index surfaces and film
thickness d ranging from d=1 (two-dimensional) up to d=8.
Using the dynamical mean-field theory, the lattice (film) problem
is self-consistently mapped onto a set of d single-impurity
Anderson models which are indirectly coupled via the respective
baths of conduction electrons. The impurity models are solved at
zero temperature using the exact-diagonalization algorithm. We
investigate the layer and thickness dependence of the electronic
structure in the low-energy regime. Effects due to the finite film
thickness are found to be the more
pronounced the lower is the film-surface coordination number.
For the comparatively open sc(111) geometry we find a strong
layer dependence of the quasi-particle weight
while it is much less pronounced for the sc(110) and the sc(100)
film geometries. For a given geometry and
thickness d there is a unique critical interaction strength
at which all effective masses diverge and there is
a unique strength
where the insulating solution
disappears.
and
gradually increase
with increasing thickness eventually approaching their bulk values.
A simple analytical argument explains the complete
geometry and thickness dependence of
.
is found
to scale linearly with
.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.30.+h – Metal-insulator transitions and other electronic transitions / 73.50.-h – Electronic transport phenomena in thin films
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999