ON THE INTRINSIC MECHANISM OF THE CENTRAL-PEAK PHENOMENA NEAR FERROELECTRIC PHASE-TRANSITIONS

A new microscopic analysis of the central-peak phenomena caused by the rmal fluctuations near the order-disorder phase transitions is given. This is based on new results obtained recently in the dynamics of the disordered phase of ferroelectrics in the framework of the three-dimen sional spin-1/2 Ising model in a transverse field and performed by the Green function method. A microscopic description for all the paramete rs of a phenomenological model adopted in the central-peak problem is given. In particular, the central-peak observation conditions are form ulated. A new critical behaviour of the central relaxation-type mode, namely gamma(c) similar to (T - T-c)(5/4) is found. A minimum of the s oft mode is predicted above the critical temperature T-c.