Activated Dynamics in the Two-Dimensional Ising Spin-Glass Rb2Cu1xCoxF4

Abstract
Activated dynamics are established in Rb2 Cu0.782 Co0.218 F4, which is a model compound for the two-dimensional Ising spin-glass with random nearest-neighbor bonds. Cole-Cole analysis of the ac complex susceptibility reveals an extremely wide distribution of relaxation times, and a divergence, extracted to cover sixteen decades, of the median relaxation time τc towards Tc=0 K according to ln(τcτ0)T1ψν, with ψν=2.2±0.2. Activated dynamic scaling of the out-of-phase susceptibility is found to hold over a wide range of temperatures and frequencies. Estimates for the critical exponents γ, ν, and ψ are given.