Mapping band alignment across complex oxide heterointerfaces

Interfaces have emerged as a key focal point in currentcondensed matter science. In complex correlated oxides,heterointerfaces provide a powerful way to design andmanipulate the charge, spin, orbital, and lattice degreesof freedom [1]. In artificially constructed heterointerfaces,the interactions between these degrees offreedom have ledto a number of exciting discoveries [2–6]. Cross-sectionalscanning tunneling microscopy and spectroscopy(XSTM/S) have recently been applied to explore the elec-tronic structures across domain walls in ferroics withatomic resolution [7]. These approaches provide directexperimental insights into the origin and nature of electri-calconductivityatthesehomointerfaces.Thepresentstudyprobes the electronic structures across the heterointerfacesbetween different materials in complex oxides using thistechnique. These heterostructured systems are challengingbecause the different band structures of the materials onbothsidesoftheinterfaceandextrinsiceffects, suchastip-sample interactions, must be taken into account [8,9].The conducting quasi-two-dimensional electron gasformed at the interface between two insulators [LaAlO