Robust Electronic Structure of Manganite-Buffered Oxide Interfaces with Extreme Mobility Enhancement.

Li, Hang; Gan, Yulin; Husanu, Marius-Adrian; Dahm, Rasmus Tindal; Christensen, Dennis Valbjørn; Radovic, Milan; Sun, Jirong; Shi, Ming et al. · ACS Nano · 2022

basic_science · Level V

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Abstract

The electronic structure as well as the mechanism underlying the high-mobility two-dimensional electron gases (2DEGs) at complex oxide interfaces remain elusive. Herein, using soft X-ray angle-resolved photoemission spectroscopy (ARPES), we present the band dispersion of metallic states at buffered LaAlO<sub>3</sub>/SrTiO<sub>3</sub> (LAO/STO) heterointerfaces where a single-unit-cell LaMnO<sub>3</sub> (LMO) spacer not only enhances the electron mobility but also renders the electronic structure robust toward X-ray radiation. By tracing the evolution of band dispersion, orbital occupation, and electron-phonon interaction of the interfacial 2DEG, we find unambiguous evidence that the insertion of the LMO buffer strongly suppresses both the formation of oxygen vacancies as well as the electron-phonon interaction on the STO side. The latter effect makes the buffered sample different from any other STO-based interfaces and may explain the maximum mobility enhancement achieved at buffered oxide interfaces.