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MA: Fachverband Magnetismus

MA 14: Magnetic Half Metals and Oxides

MA 14.10: Vortrag

Dienstag, 26. Februar 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.)