Optical spectroscopic investigation on the temperature-dependent electronic structure evolution of the Jeff,1/2 Mott insulator Sr2IrO4

We investigated the temperature-dependent evolution of the electronic structure of the Jeff,1/2 Mott insulator Sr2IrO4 using optical spectroscopy. The optical conductivity spectra $\sigma(\omega)$ of this compound has recently been found to exhibit two d-d transitions associated with the transition between the Jeff,1/2 and Jeff,3/2 bands due to the cooperation of the electron correlation and spin-orbit coupling. As the temperature increases, the two peaks show significant changes resulting in a decrease in the Mott gap. The experimental observations are compared with the results of first-principles calculation in consideration of increasing bandwidth. We discuss the effect of the temperature change on the electronic structure of Sr2IrO4 in terms of local lattice distortion, excitonic effect, electron-phonon coupling, and magnetic ordering.