Short-range quasistatic order and critical spin correlations in α-Ru1-xIrxCl3

The magnetic ground states of the diluted α-Ru1-xIrxCl3 are systematically investigated by magnetization, specific heat, and muon spin rotation measurements. Introduction of moderate spin vacancies leads to a destabilization of the zigzag antiferromagnetic order towards a short-range ordered state. It is remarkable that the x=0.2 sample located near a quantum critical point shows an extremely short correlation length of the magnitude of magnetic moments ζmag∼1.2a (a=lattice spacing) and a power-law behavior of the magnetic susceptibility χ(T)∼T-p below 14 K for μ0H ab and below 30 K for μ0H c. Our work demonstrates that the α-Ru1-xIrxCl3 system hosts a short-range, quasistatic order characterized by critical spin correlations.