Pretransitional effects at structural phase transitions

Heterogeneous coexistence of high- and low-temperature phases has been observed around structural phase transitions. We find that such intermediate states result from a cubic coupling term of the form e(1)psi(2) in the free energy, with which the dilation strain e(1) can modify the effective temperature for the order parameter (tetragonal strain) psi. We show that el is asymmetrically induced in the high- and low-temperature phases, leading to elastic stabilization of tetragonally strained domains coherently embedded in the disordered matrix.