Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 9: Poster 1
HL 9.105: Poster
Monday, March 23, 2009, 14:30–17:00, P2
MBE growth and characterisation of Heusler Alloy Ni2MnIn on (001) InAs — •Sascha Bohse, Andriy Zolotaryov, Andreas Volland, Christian Heyn, and Wolfgang Hansen — Universität Hamburg, Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, D-20355 Hamburg, Germany
We study the morphological, structural, and magnetic properties of thin Ni2MnIn Heusler films grown on (001) InAs by molecular beam epitaxy (MBE) at temperatures between 80 ∘C and 360 ∘C. The structural properties of the films with thicknesses of 20, 60, and 100 nm are studied with atomic force microscopy (AFM), X-ray reflectivity measurements (XRR), and transmission electron microscopy (TEM). For magnetization measurements SQUID magnetometry has been used. Furthermore a composition analysis of TEM crossections is provided with energy dispersive X-ray spectroscopy (EDX). The TEM investigations reveal the formation of an intermixed layer on the film/substrate interface by diffusion of As from the substrate into the Heusler deposit. The intermixing process is accompanied by a B2 to L21 phase transition between 250 ∘C - 300 ∘C and a fast morphological degradation of the Heusler films at temperatures higher than 300 ∘C. The Ni2MnIn films grown within the 250 ∘C - 300 ∘C temperature window are found to be single-crystalline with best morphological and structural quality. Interestingly, films in L21 phase are found to have a (110) surface orientation in contrast to the InAs (001) substrate crystal.