Revealing the Photocharge-Transfer Mechanism at Manganite-Buffered LaAlO₃/SrTiO₃ Interfaces by Giant Photoresponse

The photoinduced phase transition at complex oxides remains one of the very important issues because of the emergent physics and potential applications. In particular, the mechanism of charge transfer at interfaces under irradiation is challenging. Herein, the photoinduced properties of manganite-buffered LaAlO₃/SrTiO₃ interfaces with different thicknesses of the buffer layer are systematically investigated. The giant photoresponse is observed, and its relative change in resistance is about 6.24 × 10⁶% at T = 20 K for the sample with a buffer layer thickness of 4.8 nm. Moreover, the transition temperature is enhanced by increasing the thickness of the buffer layer. More importantly, the dead layer effect at the interfaces has been suppressed by using light. All these results are attributed to the charge transfer because of the octahedral tilting at low temperatures and provide a new kind of oxide-based optical devices, such as ultraviolet detectors. This piece of work will pave the way toward two-dimensional electron gas-based optoelectronic devices.