Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 14: Magnetic Half Metals and Oxides
MA 14.10: Talk
Tuesday, February 26, 2008, 12:45–13:00, EB 202
The local structure of Co2FeZ (Z=Si, Al, Ga, Ge) Heusler compounds probed by 59Co NMR — •Sabine Wurmehl1, Jürgen T. Kohlhepp1, Henk J. M. Swagten1, Bert Koopmans1, Marek Wojcik2, Christian G. F. Blum3, Benjamin Balke3, Gerhard H. Fecher3, Vadim Ksenofontov3, and Claudia Felser3 — 1Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands — 2Polish Academy of Sciences, 02-668 Warszawa, Poland — 3Johannes Gutenberg - Universität, 55099 Mainz, Germany
A thorough structural characterisation is one of the key tools in understanding the properties of spin polarised materials as the Heusler compounds Co2FeZ with Z=(Si, Al, Ge, Ga). Spin echo nuclear magnetic resonance (NMR) spectroscopy provides a tool to probe the local structure by measuring the resonance frequencies and to probe the local hyperfine fields including the unique possibility to resolve the occupation and hyperfine fields of the neighboring shells. Thus, NMR was used to study the local (magnetic) structure of Co2FeZ (Z=Al, Si, Ga, Ge) Heusler compounds, revealing different types of multiplet resonance lines for different types of Z atoms. The observed splitting of the resonance lines originates from different local environments of the 59Co nuclei. Analysis of the spectra yields the corresponding resonance frequencies and hyperfine magnetic fields as well as the spacing between consecutive resonance lines which leads to macroscopic structural models for the investigated Co2FeZ Heusler compounds with Z=(Si, Al, Ge, Ga). (This work is funded by the DFG (FG 559) TP1. SW gratefully acknowledges funding by DFG in project WU 595/1-1.)