Dresden 2009 – scientific programme

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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 13.8: Poster

Tuesday, March 24, 2009, 10:15–13:00, P1A

In situ low temperature ac-susceptibility measurements on ion bombarded AlFe thin films — •Moritz Trautvetter, Ulf Wiedwald, and Paul Ziemann — Universität Ulm, Institut für Festkörperphysik, 89069 Ulm, Germany

In its chemically ordered state (B2) Al_xFe_1−x is paramagnetic at room temperature in the composition range of 30<x<50 at% and can be switched to a ferromagnetic behavior by inducing chemical disorder [1]. For this purpose, ion irradiations are performed at various temperatures. In detail, thin films (ca. 60 nm) of AlFe (composition range as given above) were grown on Sapphire by Pulsed Laser Deposition at 300 K. As prepared Al₄₅Fe₅₅films are ferromagnetic with µ= 0,77 µ_B/per formula unit indicating a high degree of disorder. After annealing at 600^∘C for 2h under hydrogen atmosphere, a reduction of the magnetization to µ= 0,16 µ_B/f.u. is observed in accordance with the formation of an at least partially ordered B2 structure (bcc). The disorder due to the subsequent ion irradiation with 200 keV Ar⁺ ions leads to an enhancement of the AlFe magnetization. This effect is studied in situ as a function of ion fluence and temperature by means of low temperature ac-susceptometry.

[1] P. Shukla, M.Wortis, Phys Rev B 21, 159 (1980)