Spin liquid like Raman signatures in the hyperkagome iridate Na 4 Ir 3 O 8

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 ∼ 3500 cm − 1 with a bandwidth ∼ 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 the calculated Raman response where the Kitaev exchange interaction ( J K ) is much larger than the Heisenberg term J 1 ( J 1 / J K ∼ 0.1 ). A comparison with the theoretical model gives an estimate of the Kitaev exchange interaction parameter.