Visible light initiated and collapsed resistive switching in TbMnO3/Nb:SrTiO3 heterojunctions.

Simple oxide heterostructures have been fabricated by depositing TbMnO3 thin films on Nb:SrTiO3 substrates at different temperatures. Remarkable switching with an on/off resistance ratio of ~5000 is found in the sample grown at 720 °C, while only tiny resistive hysteresis can be observed in the sample grown at 650 °C. A jump switching in the I-V loop at the lower resistance state with negative bias is initiated by a visible light pulse in the sample grown at 650 °C, whereas a drop switching can be observed in the sample grown at 720 °C. A trapping-detrapping process along the TbMnO3/Nb:SrTiO3 interfaces is proposed to explain the anomalous photoresponse.