Magnetic Relaxation in the Heisenberg Spin Glass

This is the authors' abstract. We don't add key points for this paper.

On the basis of a dynamical theory for Heisenberg spin glasses the isothermal magnetic relaxation R(t) = M(t)/H after switching off a magnetic field H at t = 0 is calculated. The extreme short time relaxation shows an exponential decay with a temperature dependent relaxation time τ(T) and is essentially influenced by many‐body quantum effects in the spin glass state. An estimation of the long time relaxation yields in the qualitative agreement to experimental investigation a non‐exponential behaviour R(t) ∼ t−1/γ, where γ = 2 in an intermediate time region is found for T ≦ Tf. This anomalous relaxation is caused by a broad distribution of relaxation times owing to a distribution of local fields.