Dresden 2006 – scientific programme

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MA: Magnetismus

MA 25: Spin-Electronics I

MA 25.7: Talk

Thursday, March 30, 2006, 11:45–12:00, HSZ 103

Migration of Mn atoms by thermal treatment of ferromagnetic Mn-implanted TiO₂ single crystals — •D. Menzel¹, F. Iacomi², D. Cacaina³, I. Jursic¹, and J. Schoenes¹ — ¹Institut für Physik der Kondensierten Materie, TU Braunschweig, Germany — ²Al. I. Cuza University, Faculty of Physics, Iasi, Romania — ³Babes-Bolyai University, Faculty of Physics, Cluj-Napoca, Romania

Single crystalline rutile-type TiO₂ was doped with Mn using ion implantation in order to prevent Mn clustering. The Mn doped TiO₂-layer orders ferromagnetically at room temperature. The magnetic moment of the as implanted samples (0.3 µ_B per Mn) is reduced after an annealing process at 400^∘C but recovers after annealing at higher temperatures reaching 0.4 µ_B per Mn which indicates an incorporation of Mn atoms on substitutional sites. This interpretation is corroborated by shifts of XRD peaks and changes in the peak intensities. ESR investigations show two types of signals which do not depend on the orientation of the magnetic field and correspond to isolated Mn²⁺ (g = 1.98) and to Mn²⁺–O–Mn²⁺ (g = 2.00). In addition, four lines are strongly dependent on the orientation of the magnetic field and can be attributed to Mn⁴⁺. The well-resolved structure of Mn⁴⁺ may be interpreted in terms of the hyperfine interaction of the ⁴⁷Ti and ⁴⁹Ti ions which occupy the nearest sites along the crystalline c-axis.