Dresden 2009 – scientific programme
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MA: Fachverband Magnetismus
MA 32: Magnetic Thin Films III
MA 32.1: Talk
Thursday, March 26, 2009, 10:15–10:30, HSZ 403
Epitaxial growth of Heusler alloy cobalt iron silicide films on Si(111) and Si(001) substrates — •Marlene Zander, Kazuhide Kumakura, Achim Trampert, and Jens Herfort — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin
The Heusler alloy Co2FeSi is a promising candidate for a spin injection source into semiconductors, because of its high Curie temperature and predicted half-metallic behavior. Si has an enhanced spin lifetime and a large transport length of the electrons. In addition to its importance in electronics, Si has therefore been predicted to be a highly attractive semiconductor for spintronic devices. However, Co2FeSi has a large lattice mismatch of 4% relative to the Si(001) substrate. Here, we present our results on the fabrication as well as the structural and magnetic properties of Co2FeSi/Si(111) and -/Si(001) heterostructures grown by molecular beam epitaxy at various growth temperatures TG. We found that Co2FeSi layers were epitaxially grown on Si(111), while poly-crystalline Co2FeSi layers were formed on Si(001). As evidenced by X-ray diffraction at least B2 ordered Co2FeSi films were grown on Si(111) in a relatively narrow range between TG = 150 and 200 ∘C. Above this TG interfacial reactions set in. Reflection high energy electron diffraction and transmission electron microscopy measurements revealed the existence of different orientations of the Co2FeSi crystal on the Si(111) substrate. The layers are ferromagnetic at room temperature with the easy axis within the film plane. The magnetic anisotropy is correlated to the structural properties of the layers.