# Evidence of Slater-type mechanism as origin of insulating state in Sr2IrO4

## TL;DR

This study demonstrates that the insulating state in Sr2IrO4 arises from a Slater-type antiferromagnetic ordering rather than spin-orbit driven Mott physics, by including extended neighbor interactions in first-principles calculations.

## Contribution

It provides evidence that the insulating behavior in Sr2IrO4 is due to unconventional magnetic ordering, challenging the previous Jeff=1/2 Mott insulator model.

## Key findings

- Magnetic structure with up-up-down-down order matches experiments.
- Electronic gap and optical spectra are consistent with this magnetic ordering.
- Extended neighbor interactions are crucial for understanding the ground state.

## Abstract

For iridates with large spatially extended 5d orbitals, it may be anticipated that distant neighbor interactions would play a crucial role in their ground state properties. From this perspective, we investigate the magnetic structure of Sr2IrO4 by including interactions beyond first and second neighbors, via super cell modeling. Adopting to first-principles scalar relativistic methods, it is found that the minimum in total energy among various magnetic structures correspond to a up-up-down-down type antiferromagnetic ordering of the Ir ions for which the magnitude of the electronic gap, that of the Ir local moments and, the facsimile of the two-peaked structure in the optical conductivity spectra of Sr2IrO4 were found to be in good agreement with the experiments. The results unequivocally evidence that the origin of the electronic gap in Sr2IrO4 is due to an unconventional antiferromagnetic ordering of Ir ions, thereby classifying the system as a Slater magnet, rather than the spin-orbit coupling driven Jeff = 1/2 Mott insulator.