Photo-induced dynamics of charge ordering in La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ probed by ultrafast hard x-ray diffraction*

La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ thin films exhibit strong charge ordering due to charge disproportionation of Fe$^{3+}$/Fe$^{5+}$ ions along the [111] direction below T$_{c}$ $\sim$ 200K. In this study, a La$_{1/3}$Sr$_{2/3}$FeO$_{3}$ thin film was excited by ultrafast 355nm laser pulses, and the response of the charge ordering and the lattice was directly observed via ultrafast hard x-ray diffraction. We identified the threshold of the excitation laser fluence to melt the charge ordering diffraction peak. We also found charge ordering recovers in a few nanoseconds, faster than the lattice recovery. These findings indicate the non-thermal nature of the photo-induced dynamics of charge disordering in La$_{1/3}$Sr$_{2/3}$FeO$_{3}$.