Static and Dynamic Critical Magnetic Fields in Ising Spin-Glasses

By Monte Carlo simulations it is shown that the magnetization $M(T, H)$ of the two-dimensional nearest-neighbor Edwards-Anderson model is proportional to H^1-x, essentially independent of temperature T, for fields H<Hceq(T), with Hceq(T)∝T1/x, the exponent being x≈0.28±0.06. Irreversible behavior on a time scale t sets in for a field Hc(t) where Hc(t)Tf(t) nearly follows the De Almeida-Thouless line, although no static nonzero freezing temperature Tf exists. Consequences for the interpretation of related experimental work are discussed.