The Insulating Nature of Na2IrO3: Mott-type or Slater-type?

TL;DR

This study investigates whether Na2IrO3 is a Mott or Slater insulator by analyzing its temperature-dependent electronic structure using DFT+DMFT, revealing it exhibits characteristics of a Mott insulator with notable non-local correlations.

Contribution

The paper demonstrates that Na2IrO3 is primarily a Mott insulator but also involves significant non-local correlation effects, providing a nuanced understanding of its insulating mechanism.

Findings

Na2IrO3 remains insulating above T_N, indicating Mott-type behavior.

Photoemission spectra align with DFT+DMFT predictions for the insulating state.

Non-local correlations are important in describing Na2IrO3's electronic properties.

Abstract

We have investigated temperature-dependent electronic structures of Na2IrO3 to unravel its insulating nature. Employing the combined scheme of the density-functional theory (DFT) and the dynamical mean-field theory (DMFT), we have shown that the insulating state persists even above the Neel temperature (T_{N}), which reveals that Na2IrO3 is classified into a Mott-type insulator. The measured photoemission spectrum in the paramagnetic (PM) state is well described by the electronic structure obtained from the DFT+DMFT for the insulating state above T_{N}. The analysis of optical conductivity, however, suggests that the non-local correlation effect is also important in Na2IrO3. Therefore, Na2IrO3 is not to be a standard Mott insulator in that the extended nature and the non-local correlation effect of Ir 5d electrons are important as well in describing its electronic and magnetic properties.