Field-induced polaron formation in the Holstein-Hubbard model

• Published in: Europhysics letters Vol. 109; no. 3; pp. 37002 - p1-37002-p6
• Main Authors: Werner, Philipp, Eckstein, Martin
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences, IOP Publishing and Società Italiana di Fisica 01.02.2015; IOP Publishing
• Subjects: 71.10.-w; 71.10.Fd; Balancing; Carriers; Coupling; Direct current; Electric fields; Electronic structure; Joining; Localization; Phonons; Quasi-steady states; Spectroscopy; Time measurement
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/109/37002

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.