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Intrinsic versus extrinsic ferromagnetism in HfO2−x and Ni:HfO2−x thin films

Hildebrandt, Erwin and Yazdi, Mehrdad Baghaie and Kurian, Jose and Sharath, S. U. and Wilhelm, Fabrice and Rogalev, Andrei and Alff, Lambert (2014):
Intrinsic versus extrinsic ferromagnetism in HfO2−x and Ni:HfO2−x thin films.
In: Physical Review B, APS Publications, p. 134426, 90, (13), ISSN 1098-0121,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.90.134426],
[Article]

Abstract

We have investigated the possible evolution of an intrinsic stable ferromagnetic moment in oxygen deficient undoped and magnetically doped HfO2−x thin films grown by reactive molecular beam epitaxy. Neither oxygen vacancies nor substituted Ni in combination with such vacancies results in an observable magnetic moment for a broad range of oxygen vacancy concentrations. By combining integral and element specific magnetization measurements, we show that a fluctuating deposition rate of the magnetic dopant induces extrinsic ferromagnetism by promoting the formation of metallic clusters. We suggest the element specific measurement of an induced magnetic moment at the nonmagnetic site as a proof of intrinsic ferromagnetism in diluted magnetic semiconductors.

Item Type: Article
Erschienen: 2014
Creators: Hildebrandt, Erwin and Yazdi, Mehrdad Baghaie and Kurian, Jose and Sharath, S. U. and Wilhelm, Fabrice and Rogalev, Andrei and Alff, Lambert
Title: Intrinsic versus extrinsic ferromagnetism in HfO2−x and Ni:HfO2−x thin films
Language: English
Abstract:

We have investigated the possible evolution of an intrinsic stable ferromagnetic moment in oxygen deficient undoped and magnetically doped HfO2−x thin films grown by reactive molecular beam epitaxy. Neither oxygen vacancies nor substituted Ni in combination with such vacancies results in an observable magnetic moment for a broad range of oxygen vacancy concentrations. By combining integral and element specific magnetization measurements, we show that a fluctuating deposition rate of the magnetic dopant induces extrinsic ferromagnetism by promoting the formation of metallic clusters. We suggest the element specific measurement of an induced magnetic moment at the nonmagnetic site as a proof of intrinsic ferromagnetism in diluted magnetic semiconductors.

Journal or Publication Title: Physical Review B
Volume: 90
Number: 13
Publisher: APS Publications
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Nov 2014 13:38
Official URL: http://dx.doi.org/10.1103/PhysRevB.90.134426
Identification Number: doi:10.1103/PhysRevB.90.134426
Funders: This work was supported by DFG through Grant No. AL 560/13-1, by the LOEWE-Centre AdRIA, by ENIAC within the project PANACHE and by BMBF (project No. 16ES0250).
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