We have studied the role of interface in charge transport across \(\hbox {ZnO-rGO/La}_{0.7}\hbox {Sr}_{0.3}\hbox {MnO}_3\) (LSMO)/ITO heterostructure through impedance measurements and consequent fitting analysis of the experimental observations. The impedance data have been measured under varying magnetic field, and optical power of 660 nm red laser light. Our experimental signatures reveal contributions from both bulk and interface of the heterostructure. We have observed decrease in impedance with magnetic field up to 1.2 kOe. This decrease has been attributed to magnetic field assisted enhanced charge transport in the LSMO layer. However, at higher fields, depletion region in ZnO-rGO/LSMO interface widens, which in turn increases the charge carrier scattering thereby enhancing impedance of the heterostructure. In absence of any external magnetic field, light assisted dielectric relaxation in ZnO-rGO layer is found to be dominant up to 30.27 µW optical power. Under higher optical power, the light induced widening of ZnO-rGO/LSMO space charge region surges the charge carrier scattering, which in turn increases the impedance. In presence of constant 0.5 kOe field and varying optical power, combined effect of magnetic field and light has been observed in the impedance data. Interestingly, under simultaneous presence of 1.0 kOe field and varying optical power, a significant number of magnetic field induced defect states counterbalances the light induced increase in charge carrier scattering at moderate optical powers.
