Nonlinear optical response in a ferromagnetic insulating manganite: Pr$_{0.8}$Ca$_{0.2}$MnO$_{3}$

Abstract: High harmonic generation from Pr${0.8}$Ca${0.2}$MnO${3}$ was investigated across a high-temperature paramagnetic phase and a low-temperature ferromagnetic phase. As the temperature decreases, the harmonic intensity gradually increases in the paramagnetic phase like that in different composition material Pr${0.6}$Ca${0.4}$MnO${3}$. However, it turns to a decrease in the ferromagnetic phase. We propose a possible interpretation of the anomaly around the ferromagnetic transition temperature considering the thermal fluctuation of orbital order and the metal-insulator phase separation in the ferromagnetic insulating phase.