Field-induced polaron formation in the Holstein-Hubbard model
1 Department of Physics, University of Fribourg - 1700 Fribourg, Switzerland
2 Max Planck Research Department for Structural Dynamics, University of Hamburg-CFEL - Hamburg, Germany
Received: 6 October 2014
Accepted: 21 January 2015
We study the effect of strong DC and pulsed electric fields on a Mott insulating system with coupling to optical phonons. A DC field of the order of the gap induces a metallic state characterized by polaronic features in the gap region and a partially inverted population. In this quasi-steady state, the field-induced doublon-hole production is balanced by a phonon-enhanced doublon-hole recombination. The photo-excitation of carriers by a pulsed field leads to similar modifications of the electronic structure in the gap region, and an associated reduction of the doublon life-time. We demonstrate that the field-induced localization of electrons effectively enhances the phonon coupling, an effect which should be measureable with time-resolved photo-emission spectroscopy.
PACS: 71.10.-w – Theories and models of many-electron systems / 71.10.Fd – Lattice fermion models (Hubbard model, etc.)
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