Shining Light on Interfaces: How Boundaries Control Advanced Materials

Managing complex oxide interfaces presents significant opportunities to enhance the properties of strongly correlated heterostructures. These materials offer interesting possibilities for overcoming the physical limitations of computing technology and addressing energy-efficiency challenges. Inspired by energy conversion devices utilizing photodoped semiconductors, we propose a CdS/La_0.7Sr_0.3MnO₃ (LSMO) heterostructure system and analyze it using a variety of methods including atomic-resolution microscopy, electron energy loss spectroscopy (EELS), electrical transport, and density functional theory (DFT). Scanning Transmission Electron Microscopy−Electron Energy Loss Spectroscopy (STEM–EELS) finds oxygen diffusion and Mn intermixing at the CdS/LSMO interface, which leads to partial oxidation of CdS and promotes band bending. The transport measurement shows an abrupt, light-induced resistivity drop that is absent in bare LSMO, and this impact can be directly attributed to the coupling of the two materials at the interface. The DFT simulations support the band alignment between CdS and LSMO, and when combined with band bending of the CdS segment, the CdS/LSMO interface promotes hole injection into the LSMO, tuning the Mn³⁺:Mn⁴⁺ ratio and improving the metallic character. We proposed a transport model that quantitatively describes the experimental response verifying that interface-mediated photodoping of LSMO follows from the light-induced enhancement. These findings reveal how chemical and electronic reconstructions at oxide–semiconductor interfaces afford light control of correlated transport thereby providing pathways to future optoelectronic devices.