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Oxygen vacancies at the origin of pinned moments in oxide interfaces : The example of tetragonal CuO/SrTiO3

Bacq-Labreuil, Benjamin ; Lenz, Benjamin and Biermann, Silke LU (2022) In Physical Review B 106(23).
Abstract

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 dichroism 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, based on the formation of oxygen vacancies in the TiO2 interface layer. We show the emergence of a paramagnetic two-dimensional 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... (More)

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 dichroism 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, based on the formation of oxygen vacancies in the TiO2 interface layer. We show the emergence of a paramagnetic two-dimensional 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.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
106
issue
23
article number
235155
publisher
American Physical Society
external identifiers
  • scopus:85145256673
ISSN
2469-9950
DOI
10.1103/PhysRevB.106.235155
language
English
LU publication?
yes
id
fb502a83-a434-43ad-aed0-bbdf9a3f8276
date added to LUP
2023-01-16 15:32:58
date last changed
2025-04-04 15:06:26
@article{fb502a83-a434-43ad-aed0-bbdf9a3f8276,
  abstract     = {{<p>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 dichroism 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, based on the formation of oxygen vacancies in the TiO2 interface layer. We show the emergence of a paramagnetic two-dimensional 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.</p>}},
  author       = {{Bacq-Labreuil, Benjamin and Lenz, Benjamin and Biermann, Silke}},
  issn         = {{2469-9950}},
  language     = {{eng}},
  number       = {{23}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review B}},
  title        = {{Oxygen vacancies at the origin of pinned moments in oxide interfaces : The example of tetragonal CuO/SrTiO3}},
  url          = {{http://dx.doi.org/10.1103/PhysRevB.106.235155}},
  doi          = {{10.1103/PhysRevB.106.235155}},
  volume       = {{106}},
  year         = {{2022}},
}