Giant photoconductance at infinite-layer nickelate/SrTiO₃ interfaces via an optically induced high-mobility electron gas

Two-dimensional electron gases (2DEGs) at oxide interfaces are promising for electronics because of desirable ingredients such as spin–orbit coupling and strong correlations that can be leveraged to bridge into spintronics or photonics. In this context, the ability to manipulate oxide 2DEGs via external knobs is particularly important. Here we show that a volatile high-mobility 2DEG can be photogenerated at the interface between SrTiO₃ (001) and infinite-layer NdNiO₂, where such an electronic state is otherwise absent. This allows us to optically switch the 2DEG between ON and OFF, leading to a giant, instantaneous conductivity variation. The key ingredients for this effect are the structural and electronic reconstructions at the NdNiO₂//SrTiO₃ interface, together with a built-in interfacial electric field that promotes the occupation of the Ti 3d_xy band by the photogenerated carriers. By contributing to understanding photoconductance at complex-oxide interfaces, our results pave the way to engineer the photoresponse of strongly correlated electrons.