Abstract:
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 U c2 (d) at which all effective masses diverge and there is a unique strength U c1 (d) where the insulating solution disappears. U c2 (d) and U c1 (d) gradually increase with increasing thickness eventually approaching their bulk values. A simple analytical argument explains the complete geometry and thickness dependence of Uc2. Uc1 is found to scale linearly with Uc2.
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Received 19 August 1998
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Potthoff, M., Nolting, W. Dynamical mean-field study of the Mott transition in thin films. Eur. Phys. J. B 8, 555–568 (1999). https://doi.org/10.1007/s100510050722
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DOI: https://doi.org/10.1007/s100510050722