Interface properties and built-in potential profile of a LaCrO${}_3$/SrTiO${}_3$ superlattice determined by standing-wave excited photoemission spectroscopy

Abstract

LaCrO${}_3$ (LCO) / SrTiO${}_3$ (STO) heterojunctions are intriguing due to a polar discontinuity along (001), two distinct and controllable interface structures [(LaO)${}^{+}$/(TiO${}_2$)${}^0$ and (SrO)${}^0$/(CrO${}_2$)${}^{-}$], and interface-induced polarization. In this study, we have used soft- and hard x-ray standing-wave excited photoemission spectroscopy (SW-XPS) to generate a quantitative determination of the elemental depth profiles and interface properties, band alignments, and the depth distribution of the interface-induced built-in potentials in the two constituent oxides. We observe an alternating charged interface configuration: a positively charged (LaO)${}^{+}$/(TiO${}_2$)${}^0$ intermediate layer at the LCO${}_{\text{top}}$/STO${}_{\text{bottom}}$ interface and a negatively charged (SrO)${}^0$/(CrO${}_2$)${}^{-}$ intermediate layer at the STO${}_{\text{top}}$/LCO${}_{\text{bottom}}$ interface. Using core-level SW data, we have determined the depth distribution of species, including through the interfaces, and these results are in excellent agreement with scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS) mapping of local structure and composition. SW-XPS also enabled deconvolution of the LCO-contributed and STO- contributed matrix-element-weighted density of states (MEWDOSs) from the valence band (VB) spectra for the LCO/STO superlattice (SL). Monitoring the VB edges of the deconvoluted MEWDOS shifts with a change in probing profile, the alternating charge- induced built-in potentials are observed in both constituent oxides. Finally, using a two-step simulation approach involving first core-level binding energy shifts and then valence-band modeling, the built-in potential gradients across the SL are resolved in detail and represented by the depth distribution of VB edges.

arXiv commentMain text: 29 pages, 5 figures; Supplementary Information: 20 pages, 10 figures

References in corpus (8)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Charge transfer and interfacial magnetism in (LaNiO3)n/(LaMnO3)2 superlattices
• Energetic, spatial and momentum character of a buried interface: the two-dimensional electron gas between two metal oxides
• Interface structure, band alignment and built-in potentials at LaFeO${}_3$/$\text{n}$-SrTiO${}_3$ heterojunctions
• Dynamic Interface Rearrangement in LaFeO${}_3$ / $n$-SrTiO${}_3$ Heterojunctions
• Interface-induced Polarization in SrTiO${}_3$-LaCrO${}_3$ Superlattices
• Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)

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