Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 8: Magnetic Materials II

MA 8.5: Talk

Monday, March 26, 2007, 16:15–16:30, H22

Electronic structure, magnetism, and disorder in the Heusler compound Co₂TiSn — •Hem Chandra Kandpal¹, Vadim Ksenofontov¹, Marek Wojcik², Ram Seshadri³, and Claudia Felser¹ — ¹Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Staudinger Weg 9, 55099 Mainz, Germany — ²Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warszawa, Poland — ³Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA

Polycrystalline samples of the Heusler compound Co₂TiSn have been prepared and studied using bulk techniques (X-ray diffraction and magnetization) as well as local probes (¹¹⁹Sn Mössbauer spectroscopy and ⁵⁹Co nuclear magnetic resonance spectroscopy) in order to determine how disorder affects half-metallic behavior and also, to establish the joint use of Mössbauer and NMR spectroscopies as a quantitative probe of local atom ordering in these compounds. Additionally, density functional electronic structure calculations on ordered and partially disordered Co₂TiSn compounds have been carried out at a number of different levels of theory in order to simultaneously understand how the particular choice of DFT scheme as well as disorder affect the computed magnetization. Our studies suggest that a sample which seems well-ordered by X-ray diffraction and magnetization measurements can possess up to 10% of antisite (Co/Ti) disordering. Computations similarly suggest that even 12.5% antisite Co/Ti disorder does not destroy the half-metallic character of this material.