Photoinduced in-gap excitations in the one-dimensional extended Hubbard model

TL;DR

This study explores how a transient laser pulse affects the optical conductivity and in-gap excitations in the one-dimensional extended Hubbard model, revealing distinct behaviors in SDW and CDW phases.

Contribution

It provides a detailed analysis of photoinduced in-gap excitations and their origins in different phases using the time-dependent Lanczos method.

Findings

In-gap excitations differ between SDW and CDW phases.

Low-energy in-gap excitation in SDW is due to parity of states.

In-gap states in CDW are caused by confined photogenerated carriers.

Abstract

We investigate the time evolution of optical conductivity in the half-filled one-dimensional extended Hubbard model driven by a transient laser pulse, by using the time-dependent Lanczos method. Photoinduced in-gap excitations exhibit a qualitatively different structure in the spin-density wave (SDW) in comparison to the charge-density-wave (CDW) phase. In the SDW, the origin of a low-energy in-gap excitation is attributed to the even-odd parity of the photoexcited states, while in the CDW an in-gap state is due to confined photogenerated carriers. The signature of the in-gap excitations can be identified as a characteristic oscillation in the time evolution of physical quantities.