Antiferromagnetic resonance in the cubic iridium hexahalides (NH${}_4$)${}_2$IrCl${}_6$ and K${}_2$IrCl${}_6$

Abstract

We report on high-field electron spin resonance studies of two iridium hexahalide compounds, (NH${}_4$)${}_2$IrCl${}_6$ and K${}_2$IrCl${}_6$. In the paramagnetic state, our measurements reveal isotropic $g$-factors $g=1.79$(1) for the Ir${}^{4+}$ ions, in agreement with their cubic symmetries. Most importantly, in the magnetically ordered state, we observe two magnon modes with zero-field gaps of 11.3 and 14.2 K for (NH${}_4$)${}_2$IrCl${}_6$ and K${}_2$IrCl${}_6$, respectively. Based on that and using linear spin-wave theory, we estimate the nearest-neighbor exchange couplings and anisotropic Kitaev interactions, $J_1/k_B=10.3$ K, $K/k_B=0.7$ K for (NH${}_4$)${}_2$IrCl${}_6$, and $J_1/k_B=13.8$ K, $K/k_B=0.9$ K for K${}_2$IrCl${}_6$, revealing the nearest-neighbor Heisenberg coupling as the leading interaction term, with only a weak Kitaev anisotropy.

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Cited by in corpus (6)

• Ground state selection by magnon interactions in the fcc antiferromagnet
• Vibronic effect on resonant inelastic x-ray scattering in cubic iridium hexahalides
• Dynamic Jahn-Teller Phenomena in Heavy Transition Metal Compounds
• Spin-orbital-lattice entanglement in the ideal j=1/2 compound K${}_2$IrCl${}_6$
• Rotational phase transitions in antifluorite-type osmate and iridate compounds
• Pulling order back from the brink of disorder: Observation of a nodal line spin liquid and fluctuation stabilized order in K${}_2$IrCl${}_6$