Dynamics of photoexcited states in one-dimensional dimerized Mott insulators

TL;DR

This paper investigates the dynamics of photoexcited states in a one-dimensional dimerized Mott insulator, revealing how interdimer charge transfer excitations can destabilize the dimerized phase and induce phase transitions, with implications for organic spin-Peierls compounds.

Contribution

It provides a theoretical analysis combining numerical and perturbative methods to identify the nature of photoexcited states and their role in phase transitions in dimerized Mott insulators.

Findings

Lowest photoexcited state is an interdimer charge transfer excitation.

Photoexcited states can destabilize the dimerized phase.

Midgap states have a purely electronic origin.

Abstract

Dynamical properties of photoexcited states are theoretically studied in a one-dimensional Mott insulator dimerized by the spin-Peierls instability. Numerical calculations combined with a perturbative analysis have revealed that the lowest photoexcited state without nearest-neighbor interaction corresponds to an interdimer charge transfer excitation that belongs to dispersive excitations. This excited state destabilizes the dimerized phase, leading to a photoinduced inverse spin-Peierls transition. We discuss the purely electronic origin of midgap states that are observed in a latest photoexcitation experiment of an organic spin-Peierls compound, K-TCNQ (potassium-tetracyanoquinodimethane).