Condensed Matter Physics Seminar

Crossover from pure to random field critical properties in an Ising ferroelectric system

Don Taylor
Queen's Physics

Time
Wed. February 16, 2005     10:30 AM     Stirling 501

Abstract

The effects of random static local fields on critical properties at a phase transition have been studied extensively for many years, particularly for Ising model systems. After a period of uncertainty and controversy, the predictions of theory have become generally accepted. However experimental research on such systems has proven to be difficult and progress has been slow. After a review of phase transitions and random field effects I will describe recent experiments on a new ferroelectric realization of a random field system, KH2(As,P)O4. The precise susceptibility measurements available in a ferroelectric system have made it possible to observe a clear crossover from pure to random-field critical behaviour as a function of temperature. The results are consistent with theory that predicts that random fields essentially reduce the dimensionality of the system.

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