Crossover from charge-localized state to charge-ordered state in ${\mathrm{Pr}}_{\frac{2}{3}}{\mathrm{Ca}}_{\frac{1}{3}}\mathrm{Mn}{\mathrm{O}}_3$

In ${\mathrm{Pr}}_{\frac{2}{3}}{\mathrm{Ca}}_{\frac{1}{3}}\mathrm{Mn}{\mathrm{O}}_3$, we have found a crossover from a charge-localized state to a charge-ordered (CO) state. Linear-thermal-expansion and magnetostriction measurements up to 14 T show that for temperatures below $T_p\sim 400$ K a charge localization is present as in the case of ${\mathrm{La}}_{\frac{2}{3}}{\mathrm{Ca}}_{\frac{1}{3}}\mathrm{Mn}{\mathrm{O}}_3$. Below $T_{\mathrm{CO}}\approx 210$ K, a charge ordering, as found in some $R_{0.5}{A}_{0.5}\mathrm{Mn}{\mathrm{O}}_3$ ($R-A=\mathrm{L}\mathrm{a}-\mathrm{C}\mathrm{A},\mathrm{P}\mathrm{r}-\mathrm{C}\mathrm{a},\mathrm{P}\mathrm{r}-\mathrm{S}\mathrm{r},\mathrm{N}\mathrm{d}-\mathrm{S}\mathrm{r}$) compounds, is observed. A magnetic field suppresses the CO state below $T_{\mathrm{CO}}$ giving rise to a first-order structural transition. A continuous change in volume is measured between $T_{\mathrm{CO}}<T<\mathrm{}{T}_p$. The electrical behavior is similar to the structural behavior, and is the result of the strong spin-charge-lattice coupling present in the colossal-magnetoresistance perovskites.