Abstract
The insulating honeycomb magnet α−RuCl3 exhibits fractionalized excitations that signal its proximity to a Kitaev quantum spin liquid state; however, at T=0 , fragile long-range magnetic order arises from non-Kitaev terms in the Hamiltonian. Spin vacancies in the form of Ir3+ substituted for Ru are found to destabilize this long-range order. Neutron diffraction and bulk characterization of Ru1−xIrxCl3 show that the magnetic ordering temperature is suppressed with increasing x , and evidence of zigzag magnetic order is absent for x>0.3 . Inelastic neutron scattering demonstrates that the signature of fractionalized excitations is maintained over the full range of x investigated. The depleted lattice without magnetic order thus hosts a spin-liquid-like ground state that may indicate the relevance of Kitaev physics in the magnetically dilute limit of RuCl3 .
