  The strongly correlated material La0.7Sr0.3MnO3 (LSMO) exhibits
metal-to-insulator and magnetic transition near room temperature. Although the
physical properties of 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 (CdS) to an LSMO layer to change its electrical conductivity. LSMO
exhibits no significant optical response, however, the CdS/LSMO
heterostructures show an enhanced conductivity, with ~ 37 % resistance drop, 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
LSMO. Surprisingly, the optical and magnetic responses of CdS/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.
