Random‐field experiments in dilute antiferromagnets

Experiments in d = 2 and d = 3 random-field Ising systems are reviewed. Random fields destroy the phase transition for the d = 2 system Rb2Co x Mg1-xF4. The d = 3 Fe x Zn1-xF4 system shows a new phase transition with unusual dynamics. Extreme critical slowing down plays an essential role in the d = 3 measurements. Experiments on the related d = 3 systems Mn x Zn1-xF2 and Fe x Mg1-xC12 are also discussed.