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MA: Fachverband Magnetismus

MA 7: Magnetic Semiconductors

MA 7.3: Vortrag

Montag, 16. März 2015, 12:00–12:15, EB 202

Intrinsic versus extrinsic ferromagnetism in HfO_2−x and Ni:HfO_2−x thin films — •Erwin Hildebrandt¹, Mehrdad Baghaie Yazdi¹, Jose Kurian¹, S. U. Sharath¹, Fabrice Wilhelm², Andrei Rogalev², and Lambert Alff¹ — ¹Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt, Germany — ²European Synchrotron Radiation Facility (ESRF), BP 220, 38043 Grenoble Cedex 9, France

We have investigated the possible evolution of an intrinsic stable ferromagnetic moment in oxygen deficient undoped and magnetically doped HfO_2−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 non-magnetic site as an unambiguous proof of intrinsic ferromagnetism in diluted magnetic semiconductors.[1]

[1] E. Hildebrandt, M. Baghaie Yazdi, J. Kurian, S. U. Sharath, F. Wilhelm, A. Rogalev, and L. Alff, Phys. Rev. B 90, 134426 (2014)