Renormalization of the heat-diffusion central peak in KH2PO4

Light-Scattering measurements of energy fluctuations coupled to order-parameter fluctuations by an applied electric field are presented. A firm experimental demonstration of the static and dynamic properties of the central-peak equation is obtained. Immediately above the transition both the specific heat and the thermal diffusivity extrapolated to zero field are found to be temperature independent. The specific heat agrees with the lattice value, whereas the diffusivity appears anomalously small. © 1981 The American Physical Society.