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In the pursuit of novel functionalities by utilizing the lattice degree of freedom in complex oxide heterostructure, the control mechanism through direct strain manipulation across the interfaces is still under development, especially with various stimuli, such as electric field, magnetic field, light, etc. In this study, the superlattices consisting of colossal-magnetoresistive manganites La0.7Sr0.3MnO3 (LSMO) and photostrictive SrRuO3 (SRO) have been designed to investigate the light-dependent controllability of lattice order in the corresponding functionalities and rich interface physics. Two substrates, SrTiO3 (STO) and LaAlO3 (LAO), have been employed to provide the different strain environments to the superlattice system, in which the LSMO sublayers exhibit different orbital occupations. Subsequently, by introducing light, we can modulate the strain state and orbital preference of LSMO sublayers through light-induced expansion of SRO sublayers, leading to surprisingly opposite changes in photoresistivity. The observed photoresistivity decreases in the superlattice grown on STO substrate while increases in the superlattice grown on LAO substrate under light illumination. This work has presented a model system that demonstrates the manipulation of orbital–lattice coupling and the resultant functionalities in artificial oxide superlattices via light stimulus.

Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, we study the non-linear optical properties of single crystal inorganic-organic hybrid perovskite CH3NH3PbBr3. By exciting the material with a 1044 nm laser, we were able to observe strong two-photon absorption-induced photoluminescence in the green spectral region. Using the transmission open-aperture Z-scan technique, we estimated the values of the two-photon absorption coefficient to be 8.5 cm GW-1, which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as LiNbO3, LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as reduce noise, and can be used to strongly control the intensity of incident light. In this study, we demonstrate the superior optical limiting, pulse reshaping, and stabilization properties of CH3NH3PbBr3, opening new applications for perovskites in nonlinear optics.