Energy gap in concentrated spin glasses

Using magnetic resonance data at several frequencies, we have obtained the temperature dependence of the field-induced magnetization (M) in three concentrated spin glasses. At every frequency, M is independent of T for T≲TSG and drops linearly with T at higher temperatures. [M(0)−M(T)]/M(0) is closely represented by the function [exp(Δ/T)−1]−1, where Δ is a characteristic gap energy with values close to the corresponding Curie–Weiss temperatures θp but much larger than the respective spin-glass transition temperatures TSG.