Defect assisted magneto-tunable photoresponse in ZnO-rGO/La0.7Sr0.3MnO3/ITO heterojunctions

We have investigated light and magnetic field dependent electrical transport response of (100-x)%ZnO-x%rGO/La0.7Sr0.3MnO3 (LSMO)/ITO (x = 0, 100, 0.6, 0.8) heterostructure devices at room temperature. Negative and positive magnetoresistance(MR) response, respectively for bare (x = 0, 100) and composite devices (x = 0.6, 0.8) is associated with spin dependent scattering at eg2 up arrow and t2g down arrow band of LSMO space charge region. Positive bias current, for bare devices, is supposed to have a defect induced suppression with light leading to an overall decrease of device current at low field. However, the bias current may have started increasing with light at high fields thereby reversing photosensitivity sign from negative (NPS) to positive (PPS). Such reversal from NPS to PPS has been attributed to high defect induced carrier transport through depinning of electrons from weak pinning centers with magnetic field. (100-x)%ZnO-x%rGO/LSMO barrier widths that are directly proportional with defect state population seem to support field induced change of photosensitivity behavior with light illumination.

Automated summary

We investigated the electrical transport response of (100-x)%ZnO-x%rGO/La0.7Sr0.3MnO3 (LSMO)/ITO heterostructure devices under light and magnetic field at room temperature. The magnetoresistance (MR) response showed negative and positive behavior for bare and composite devices, respectively, due to spin-dependent scattering in the LSMO space charge region. The bias current in bare devices exhibited defect-induced suppression with light, resulting in an overall decrease in device current at low fields. However, at high fields, the bias current started increasing with light, leading to a reversal of photosensitivity from negative to positive.