Scaling and critical slowing down in random field Ising system.

A simple scaling description of the ordering transition in random field Ising systems is developed and supported by renormalization group arguments in terms of a zero temperature critical fixed point. The main prediction is that the characteristic relaxation time tau, will diverge extremely rapidly as the critical point is approached: Tau ~ exp(xi(theta)) with xi the correlation length and theta the "violation of hyperscaling" exponent (d-theta) nu = 2-a. Recent experiments which exhibit onset of hysteresis in a very narrow temperature range are discussed.