Spin liquid like Raman signatures in hyperkagome iridate Na$_4$Ir$_3$O$_8$

TL;DR

This study combines Raman scattering experiments and theoretical calculations to demonstrate that Kitaev-like magnetic interactions dominate in the hyperkagome iridate Na$_4$Ir$_3$O$_8$, indicating potential quantum spin liquid behavior.

Contribution

It provides the first combined experimental and theoretical evidence for dominant Kitaev interactions in Na$_4$Ir$_3$O$_8$, a hyperkagome iridate.

Findings

Observation of a broad Raman band at ~3500 cm$^{-1}$

Kitaev exchange interaction is much larger than Heisenberg term

Estimated Kitaev exchange parameter from model comparison

Abstract

Combining Raman scattering measurements with mean field calculations of the Raman response we show that Kitaev-like magnetic exchange is dominant in the hyperkagome iridate Na$_4$Ir$_3$O$_8$. In the measurements we observe a broad Raman band at $\sim$~3500 cm$^{-1}$ with a band-width $\sim 1700$~cm$^{-1}$. Calculations of the Raman response of the Kitaev-Heisenberg model on the hyperkagome lattice shows that the experimental observations are consistent with calculated Raman response where Kitaev exchange interaction ($J_K$) is much larger than the Heisenberg term J$_1$ ($J_1/J_K \sim 0.1$). A comparison with the theoretical model gives an estimate of the Kitaev exchange interaction parameter.