Title: High-Frequency Analysis of Effective Interactions and Bandwidth for Transient States after Monocycle Pulse Excitation of Extended Hubbard Model,
Abstract: Using a high-frequency expansion in periodically driven extended Hubbard
models, where the strengths and ranges of density-density interactions are
arbitrary, we obtain the effective interactions and bandwidth, which depend
sensitively on the polarization of the driving field. Then, we numerically
calculate modulations of correlation functions in a quarter-filled extended
Hubbard model with nearest-neighbor interactions on a triangular lattice with
trimers after monocycle pulse excitation. We discuss how the resultant
modulations are compatible with the effective interactions and bandwidth
derived above on the basis of their dependence on the polarization of
photoexcitation, which is easily accessible by experiments. Some correlation
functions after monocycle pulse excitation are consistent with the effective
interactions, which are weaker or stronger than the original ones. However, the
photoinduced enhancement of anisotropic charge correlations previously
discussed for the three-quarter-filled organic conductor
$\alpha$-(bis[ethylenedithio]-tetrathiafulvalene)$_2$I$_3$
[$\alpha$-(BEDT-TTF)$_2$I$_3$] in the metallic phase is not fully explained by
the effective interactions or bandwidth, which are derived independently of the
filling.