Dynamical mean-field study of the Mott transition in thin films
Institut für Physik,
Humboldt-Universität zu Berlin,
Invalidenstrasse 110, 10115 Berlin,
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