Probing the polar-nonpolar oxide interfaces using resonant x-ray standing wave techniques

TL;DR

This paper reviews recent advancements in using resonant standing wave x-ray techniques to probe the electronic structure of buried polar-nonpolar oxide interfaces with high depth resolution, revealing interfacial phenomena.

Contribution

It highlights the application of SW-XPS and SW-RIXS techniques for depth-resolved analysis of electronic states at oxide interfaces, demonstrating Angstrom-level precision.

Findings

Enhanced spectral response near TM absorption resonances

Ability to map electronic/orbital states with Angstrom accuracy

Potential to uncover interfacial electronic phenomena

Abstract

Transition metal (TM) oxide heterostructure superlattices have attracted great attention in research communities because of their emergent interfacial phenomena that do not exist in the bulk form. In order to understand the mechanisms that cause these phenomena, it is important to use depth-resolved spectroscopies to study the electronic structure across the buried oxide interfaces. In this review, we focus on the recent applications of standing wave (SW) photoemission (SW-XPS) and resonant inelastic x-ray scattering (SW-RIXS) spectroscopy to study the depth profiles of electronic structure or carriers around the polar-nonpolar oxide interfaces. Using the incident photon energies near the TM x-ray absorption resonance, the created SW excitation can enhance the spectral response and certain electronic transitions, providing important insight into the interfacial electronic structure in the energy and real space regimes. Following the background introductions, we describe two SW experiments and demonstrate that the combination of SW-XPS and SW-RIXS has the potential to obtain the depth distribution of electronic/orbital states around the buried interfaces with Angstrom precision.