Experiments over a long range of frequencies reveal that the critical dynamics of random-field Ising models is dominated by activated hopping but the relevant exponent is quite different from the theoretical expectations based on the zero-temperature fixed point. We show that a careful application of dynamic scaling, and zero-temperature fixed point leads to an ever present ‘‘correction to scaling,’’ which causes the measured exponent to differ strongly from the expected value.

• Received 19 August 1993

DOI:https://doi.org/10.1103/PhysRevB.49.6350