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arXiv · 1802.05659

Photo-excited states in correlated band insulators

Nagamalleswararao Dasari·Martin Eckstein
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Abstract

We study the photo-excitation dynamics of correlated band insulators, using non-equilibrium dynamical mean-field theory for the ionic Hubbard model. We find two distinct behaviors, depending on the ratio of the on-site interaction $U$ and the bare band gap $Δ$. For small interactions, the relaxation is characterized by intra-band carrier scattering in relatively rigid bands, leading to a non-thermal intermediate state with separate thermal distributions of electrons and holes. This behavior can be viewed as typical for a band insulator with weak interactions. For larger interaction, on the other hand, we observe a strong modification of the electronic spectrum and a filling-in of the gap after photo-excitation, along with a rapid thermalization of the system. The two behaviors therefore provide a dynamical distinction of a correlated band insulator and a band-insulator, which can differ even when the spectra of the two systems are similar in equilibrium. The crossover happens when the interaction $U$ is comparable to $Δ$.

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Nagamalleswararao Dasari, Martin Eckstein. 2018-02-15. Photo-excited states in correlated band insulators. https://doi.org/10.1103/physrevb.98.035113

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