DYNAMICS OF THE STRAIN-MEDIATED PHASE-TRANSITION IN KDCO3 - A THERMAL-NEUTRON SPIN-ECHO STUDY

The dynamical aspects of the order-disorder phase transition in KDCO3 are studied by means of thermal-neutron spin-echo triple-axis spectrom etry with a high-energy resolution of similar to 0.2 mu eV. Besides th e critical slowing down of the correlated fluctuations of the (DCO3)(2 ) dimers, temperature-dependent fluctuations of the strain field cause d by the individual low-symmetry dimers are seen in the form of dynami cal Huang scattering around the main Bragg peak. An interesting mechan ism for the order-disorder phase transition, namely a strain-mediated phase transition, is examined from a dynamical point of view.