Behavior of SrTiO3near the [100]-Stress-Temperature Bicritical Point

Abstract

Good polydomain SrTi${\mathrm{O}}_3$ samples show, for $T\to {T_a}^{+}$, paramagnetic resonance-linewidth broadening $\Delta H\left(T\right)\mathrm{}$ of the ${\mathrm{Fe}}^{3+}$-$V_0$ center which is the average of $\Delta H_{\parallel }\mathrm{}\left(T\right)\mathrm{}$ and $\Delta H_{\perp }\mathrm{}\left(T\right)\mathrm{}$ of monodomain samples. Application of [110] and [100] stress on these samples enhances and reduces $\Delta H\left(T\right)\mathrm{}$, respectively. This verifies the Ising and Heisenberg character of the transition in monodomain and annealed samples, respectively. In the Ising monodomain case the correction to the scaling exponent of the order parameter is found to be $x>\mathrm{}0.5\mathrm{}$ in agreement with renormalization group theory.