Magnetic excitations in a three-orbital model for the strongly spin-orbit coupled iridates: Effect of mixing between the $J=\frac{1}{2}$ and $\frac{3}{2}$ sectors

Magnetic excitations in a three-orbital model for the strongly spin-orbit coupled iridates: Effect of mixing between the $J = \frac{1}{2}$ and $\frac{3}{2}$ sectors

Shubhajyoti Mohapatra, Jeroen van den Brink, and Avinash Singh

Phys. Rev. B 95, 094435 – Published 31 March 2017

Abstract

A three-orbital-model approach for studying spin-wave excitations in the strongly spin-orbit coupled layered perovskite iridates is presented which provides a unified description of magnetic excitations as well as the electronic band structure. The calculated spin-wave dispersions with realistic three-band parameters are in excellent agreement with the resonant inelastic x-ray scattering (RIXS) data for iridates, including the strong antiferromagnet zone-boundary dispersion in the single-layer compound ${Sr}_{2} {IrO}_{4}$ and the large anisotropy gap in the bilayer compound ${Sr}_{3} {Ir}_{2} O_{7}$ . The RIXS spin-wave data are shown to provide evidence of mixing between the $J = \frac{1}{2}$ and $\frac{3}{2}$ sectors in both compounds.