Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 6: Magnetic Thin Films I (Heusler Alloys)

MA 6.5: Vortrag

Montag, 22. März 2010, 15:30–15:45, H10

Growth of epitaxial thin films of Co₂MnSi and Cu₂MnAl by solid-state crystallization from the x-ray amorphous state. — •Denise Erb, Gregor Nowak, Kurt Westerholt, and Hartmut Zabel — Ruhr-Universität Bochum

Ferromagnetic Heusler alloys have attracted considerable interest recently, since the full spin polarization at the Fermi level in some of these compounds makes them promising candidates for spintronic applications. Using UHV magnetron sputtering at room temperature and subsequent annealing we have prepared thin films of the Heusler phases Co₂MnSi and Cu₂MnAl on MgO (100) and Al₂O₃ (a-plane) substrates. The structural properties were studied by synchrotron-based x-ray diffraction; the magnetic properties were investigated by vibrating sample magnetometry. In the as-prepared state the films are atomically disordered and non-magnetic. Upon annealing ferromagnetism develops together with the crystalline structure. Co₂MnSi films grown on Al₂O₃ (a-plane) and different seedlayers exhibit only the (220) Bragg reflection, indicating a long-range order of the A2-type after annealing. However, the ferromagnetic quality of these samples evidences a short-range L2₁ order. Cu₂MnAl can be grown directly on MgO (100) with the in-plane [100]-direction rotated by 45^∘ from the [100]-direction in MgO. The presence of the (111) Bragg reflection in Cu₂MnAl samples proves the epitaxial quality and a long-range L2₁ order in the annealed state.