Birefringence of SrTiO3 produced by the 105°K structural phase transition

Accurate birefringence measurements on monodomain SrTiO3 platelets give important information about the fluctuations associated with the second-order structural phase transition. Above the transition, the monodomain character is announced by a birefringence tail caused by anisotropic fluctuations. Because of these, a distinct cusp is observed at the transition temperature Ta. Below Ta, the difference aÏc2a-aÏa2a between mean-square rotations Ïc associated with the order parameter and orthogonal rotations Ïa is obtained. © 1972 The American Physical Society.