Titanium 3d ferromagnetism with perpendicular anisotropy in defective anatase

This work focuses on the generation of ferromagnetism at the surface of anatase TiO2 films by low-energy ion irradiation. Controlled Ar+-ion irradiation resulted in a thin (∼10) nm ferromagnetic surface layer. The intrinsic origin and robustness of the magnetic order has been characterized by x-ray...

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Bibliographic Details
Published in:Physical review. B 2020-01, Vol.101 (1), p.1
Main Authors: Stiller, Markus, N'Diaye, Alpha T, Ohldag, Hendrik, Barzola-Quiquia, José, Esquinazi, Pablo D, Amelal, Thomas, Bundesmann, Carsten, Spemann, Daniel, Trautmann, Martin, Chassé, Angelika, Hamed, Hichem Ben, Adeagbo, Waheed A, Hergert, Wolfram
Format: Article
Language:English
Subjects:
Anatase
Anisotropy
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Defects
Density functional calculations
Density functional theory
Dichroism
Domain walls
Ferromagnetism
Ion irradiation
Irradiation effects
Magnetic anisotropy
Magnetic domains
Magnetic fields
Magnetism
Magnetization
Remanence
Room temperature
Superconducting quantum interference devices
Surface layers
Titanium
Titanium dioxide
X-ray magnetic circular dichroism
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Summary:This work focuses on the generation of ferromagnetism at the surface of anatase TiO2 films by low-energy ion irradiation. Controlled Ar+-ion irradiation resulted in a thin (∼10) nm ferromagnetic surface layer. The intrinsic origin and robustness of the magnetic order has been characterized by x-ray magnetic circular dichroism at room temperature revealing that a Ti band is spin-polarized. These results, together with density functional theory calculations, indicate that Ti vacancy-interstitial pairs are responsible for the magnetic order. Superconducting quantum interference device measurements show the existence of a perpendicular magnetic anisotropy and a low remanent magnetization. Magnetic force microscopy reveals that this low remanence is due to oppositely aligned magnetic domains with magnetization vectors normal to the main surface. The weak domain-wall pinning, the magnetic anisotropy, together with the simplicity of the preparation method, open up interesting possibilities for future applications. As an example, single domain patterns of ∼1μm width and several μm length can be easily prepared.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.101.014412