Lattice and surface effects in the out-of-equilibrium dynamics of the Hubbard model

Patrice André, M. Schiró, and Michele Fabrizio
Phys. Rev. B 85, 205118 – Published 10 May 2012

Abstract

We study, by means of the time-dependent Gutzwiller approximation, the out-of-equilibrium dynamics of a half-filled Hubbard-Holstein model of correlated electrons interacting with local phonons. Inspired by pump-probe experiments, where intense light pulses selectively induce optical excitations that trigger a transient out-of-equilibrium dynamics, here we inject energy in the Hubbard bands by a nonequilibrium population of empty and doubly-occupied sites. We first consider the case of a global perturbation, acting over the whole sample, and find evidence of a mean-field dynamical transition where the lattice gets strongly distorted above a certain energy threshold, despite the weak strength of the electron-phonon coupling by comparison with the Hubbard repulsion. Next, we address a slab geometry for a correlated heterostructure and study the relaxation dynamics across the system when the perturbation acts locally on the first layer. While for weak deviations from equilibrium the excited surface is able to relax by transferring its excess energy to the bulk, for large deviations, the excess energy stays instead concentrated in the surface layer. This self-trapping occurs both in the absence as well as in the presence of electron-phonon coupling. Phonons actually enforce the trapping by distorting at the surface.

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  • Received 20 February 2012

DOI:https://doi.org/10.1103/PhysRevB.85.205118

©2012 American Physical Society

Authors & Affiliations

Patrice André1, M. Schiró2, and Michele Fabrizio1,3

  • 1International School for Advanced Studies (SISSA) and CNR-IOM Democritos, Via Bonomea 265, I-34136 Trieste, Italy
  • 2Princeton Center for Theoretical Science and Department of Physics, Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544, USA
  • 3The Abdus Salam International Centre for Theoretical Physics (ICTP), P.O. Box 586, I-34014 Trieste, Italy

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Issue

Vol. 85, Iss. 20 — 15 May 2012

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