Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: Computational Materials Modelling II - Methods

MM 8.1: Vortrag

Montag, 26. März 2012, 11:45–12:00, TC 006

Discontinuous epitaxial Bain paths and consequences for coherent epitaxial growth — •Stephan Schönecker, Manuel Richter, Klaus Koepernik, and Helmut Eschrig — IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany

Strained coherent epitaxy is a valuable mean to influence structural, electronic, magnetic and optical properties of bulk-like films as a function of symmetry and in-plane lattice spacings of the substrate. A remarkable example are 50 nm thick films of body centred tetragonal (BCT) Fe₇₀Pd₃₀, whose ferromagnetic properties, e.g. magnetic moment and magnetic anisotropy, can be tuned by the choice of the substrate (Buschbeck et al., PRL 103, 216101 (2009)). This tuning extends over a wide range of tetragonal distortion in the film, 1.09≤ c/a ≤ 1.54 (Kaufmann-Weiss et al., PRL 107, 206105 (2011)).

From the point of theory, an epitaxial Bain path (EBP) models the bulk part (i.e. the interior) of films in BCT structure coherently grown on substrates with four-fold symmetry by establishing a relationship between the substrate lattice parameter, a, and the out-of-plane lattice parameter of the film, c (Alippi et al., PRL 78, 3892 (1997)). We show in this contribution using several examples of the transition metal family, that c need not be a continuous function of a, hence the c/a ratio in BCT films of these elements cannot continuously be adjusted giving rise to a discontinuous EBP. Calculations of the electronic structure in the framework of density functional theory were carried out in the implementation of the full potential local orbital program package FPLO (www.fplo.de).