Light-Induced Decoupling of Electronic and Magnetic Properties in Manganites

Abstract

The strongly correlated material ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{Mn}\mathrm{O}}_{3}$ ($\mathrm{LSMO}$) exhibits metal-to-insulator and magnetic transition near room temperature. Although the physical properties of $\mathrm{LSMO}$ can be manipulated by strain, chemical doping, temperature, or magnetic field, they often require large external stimuli. To include additional flexibility and tunability, we developed a hybrid optoelectronic heterostructure that uses photocarrier injection from cadmium sulfide ($\mathrm{Cd}\mathrm{S}$) to an $\mathrm{LSMO}$ layer to change its electrical conductivity. $\mathrm{LSMO}$ exhibits no significant optical response; however, the $\mathrm{Cd}\mathrm{S}/\mathrm{LSMO}$ heterostructures show an enhanced conductivity, with a resistance drop of about 37%, at the transition temperature under light stimuli. This enhanced conductivity in response to light is comparable to the effect of a 9 T magnetic field in pure $\mathrm{LSMO}$. Surprisingly, the optical and magnetic responses of $\mathrm{Cd}\mathrm{S}/\mathrm{LSMO}$ heterostructures are decoupled and exhibit different effects when both stimuli are applied. This unexpected behavior shows that heterostructuring strongly correlated oxides may require a new understanding of the coupling of physical properties across the transitions and provide the means to implement new functionalities.