LOW-TEMPERATURE DYNAMICS OF A DILUTED ISING ANTIFERROMAGNET

We report the low-temperature dynamics of a diluted Ising antiferromag net (Fe0.46Zn0.54F2) over a wide range of magnetic fields. By measurin g the magnetization through a number of cooling protocols, we deduce t he density of antiferromagnetic domain walls, which can be compared wi th predictions of the random-field Ising model (RFIM). In both magneti zation-relaxation and field-cycling experiments, we find a region of t he (H,T) phase diagram in which the dynamic behavior is consistent wit h the RFIM, as well as a theoretically unexpected region of frozen dyn amics.