SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 21: Correlated Electrons: Electronic Structure Calculations
TT 21.3: Vortrag
Dienstag, 28. März 2023, 10:00–10:15, HSZ 201
Oxygen vacancies at the origin of pinned moments in oxide interfaces: the example of tetragonal CuO/SrTiO3 — •Benjamin Bacq-Labreuil1, Benjamin Lenz2, and Silke Biermann3 — 1Institut Quantique, Université de Sherbrooke, Sherbrooke, Canada — 2Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, Paris, France — 3Centre de Physique Théorique, Ecole Polytechnique, Palaiseau, France
Obtaining an accurate theoretical description of the emergent phenomena in oxide heterostructures is a major challenge. Recently, intriguing paramagnetic spin and pinned orbital moments have been discovered by x-ray magnetic circular dichroïsm measurements at the Cu L2,3-edge of a tetragonal CuO/SrTiO3 heterostructure. Using first principles calculations, we propose a scenario that explains both types of moments [1], based on the formation of oxygen vacancies in the TiO2 interface layer. We show the emergence of a paramagnetic 2D electron gas hosted in the interface CuO layer. It is invisible at the Ti L2,3-edge since the valence of the Ti atoms remains unchanged. Strong structural distortions breaking both the local and global fourfold rotation C4 symmetries at the interface lead to the in-plane pinning of the Cu orbital moment close to the vacancy. Our results, and in particular the pinning of the orbital moment, may have implications for other systems, especially monoxide/dioxide interfaces with similar metal-oxygen bond length and weak spin-orbit coupling.
[1] B. Bacq-Labreuil, et al, arXiv:2210.15084 (2022).