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A strong electrical field can induce a current-carrying (metallic)
state in a Mott insulator. This phenomenon is the many-body
analog of the well-known Landau-Zener breakdown of band
insulators. We investigate the problem by means of
nonequilibrium dynamical mean-field theory (DMFT), using a
recently developed impurity solver that is based on a systematic
perturbation expansion in the hybridization [1]. The
field-induced current is found to increase with a threshold
behavior exp(E/Eth), where the threshold field Eth vanishes at
the metal-insulator transition [2]. Furthermore, the DMFT
calculation reveals a field-enhanced decay of the thermal
(linear response) current in the system if the system is not
coupled to an external environment, which may be important
to understand the field-induced current switching that is
observed in several Mott insulating materials.
[1] M. Eckstein, and P. Werner, Phys. Rev. B 82, 115115 (2010). [2] M. Eckstein, T. Oka, and P. Werner, Phys. Rev. Lett. 105, 146404 (2010). |
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