NQR investigation of low frequency spin dynamics in Kitaev spin liquid candidate material Cu₂IrO₃ in zero magntic field

Cu₂IrO₃ [1] is a Kitaev spin liquid candidate material with nearly ideal honeycomb planes consisting of Ir magnetic moments, and does not exhibit a bulk magnetic long range order. We report ^63,65Cu Nuclear Quadrupole Resonance (NQR) investigation of Cu₂IrO₃ in zero external magnetic field [2]. Unlike the case of the celebrated sister compound Na₂IrO₃ or α-RuCl₃ with a bulk antiferromagnetic ground state below T_N, spin dynamics reflected on the NMR relaxation rate 1/T₁ does not show a divergent behavior caused by conventional magnons. We can therefore probe the intrinsic low energy spin excitations of the Kitaev planes using NQR in zero magnetic field in a broad window of temperature.

[1] M. Abramchuk, F. Tafti et al., JACS 139, 15371 (2017).
[2] S. K. Takahashi, J. Wang et al., preprint (to be published).