Birefringence of SrTiO3Produced by the 105°K Structural Phase Transition

Abstract

Accurate birefringence measurements on monodomain SrTi${\mathrm{O}}_3$ 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 $T_a$. Below $T_a$, the difference $〈\varphi _c^{}{}_{}{}^2〉-〈\varphi _a^{}{}_{}{}^2〉$ between mean-square rotations ${\varphi }_c$ associated with the order parameter and orthogonal rotations ${\varphi }_a$ is obtained.