Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.44: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1A

Ferromagnetic order above room temperature in cubic Y-stabilized ZrO₂ by Fe-implantation — •Monika Kotzian, Dirk Menzel, and Joachim Schoenes — Institut für Physik der Kondensierten Materie, TU Braunschweig, Germany

Diluted magnetic oxides have attracted much interest when room-temperature ferromagnetism was observed e. g. in transition metal doped TiO₂ and SnO₂. Recently, ferromagnetic order with Curie temperatures far above 300 K was also predicted in ZrO₂ when it is doped with magnetic transition elements [1]. For an experimental verification of this prediction single crystalline Y-stabilized ZrO₂ was doped with Fe using the ion-implantation technique at high doses leading to Fe concentrations up to 7 at.%. This method was chosen in order to prevent the clustering of the magnetic ions. Due to the implantation the ZrO₂ crystals show a brownish color. However, the fundamental band gap of 4.08 eV, which was determined using optical spectroscopy, does not change significantly on doping within the investigated Fe concentration range. The ZrO₂ crystals doped with 7 at.% Fe order ferromagnetically with an ordered moment per Fe atom of 0.30 µ_B at 10 K and 0.25 µ_B at room temperature. Upon annealing the brownish color vanishes and the ordered moment decreases. This leads to the interpretation of a polaron-mediated magnetic exchange interaction.

[1] S. Ostanin et al., Phys. Rev. Lett. 98, 016101 (2007).