Temperature and Dimensionality Dependences of Optical Absorption Spectra in Mott Insulators

TL;DR

This study examines how temperature influences optical absorption spectra in 1D and 2D Mott insulators, revealing dimensionality-dependent behaviors linked to charge-spin interactions.

Contribution

It provides a comparative analysis of temperature effects on optical spectra in 1D and 2D Mott insulators using an effective Hubbard model.

Findings

In 1D, the absorption edge is nearly temperature-independent.

In 2D, the absorption edge shifts to lower energy as temperature increases.

The differences are due to charge-spin coupling variations between dimensions.

Abstract

We investigate the temperature dependence of optical absorption spectra of one-dimensional (1D) and two-dimensional (2D) Mott insulators by using an effective model in the strong-coupling limit of a half-filed Hubbard model. In the numerically exact diagonalization calculations on finite-size clusters, we find that in 1D the energy position of the absorption edge is almost independent of temperature, while in 2D the edge position shifts to lower energy with increasing temperature. The different temperature dependence between 1D and 2D is attributed to the difference of the coupling of the charge and spin degrees of freedom. The implications of the results on experiments are discussed in terms of the dimensionality dependence.