Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 14: Poster Ib: Magnetic Materials (1-14); Micro Magnetism/Computational Mag. (15-17); Surface Magnetism (18-22); Spin Structures/Phase Transitions (23-25)
MA 14.5: Poster
Dienstag, 24. März 2009, 10:15–13:00, P1B
Magnetic properties of the system Fe1-xCoxSi studied by Mössbauer spectroscopy — •Josefin Engelke1, Dirk Menzel1, Jan Kreitlow1, Mathias Thede1, Gregor Bransky1, Joachim Schoenes1, Jochen Litterst1, Dalber Sanchez2, Yutao Xing2, and Elisa Baggio Saitovitch2 — 1IPKM, TU Braunschweig, Germany — 2CBPF, Rio de Janeiro, Brazil
The system Fe1-xCoxSi has been studied since many years also using Mössbauer spectroscopy amongst others methods. From magnetization one can follow the development of magnetic ordered moments depending on Co concentration, from pure FeSi which is paramagnetic down to lowest temperatures, to very small ferromagnetic moments at intermediate concentrations with maximum ordering temperatures around 50 K, and finally diamagnetism in CoSi. This development is related to changes in the electronic band structure with rather narrow gaps. For low Co concentrations a helical structure of Co moments is derived which however is modified already in weak magnetic fields to a conical structure.
A long standing question concerns the moment at iron. In order to receive more reliable information on the magnetic state of iron in zero magnetic field we have performed Mössbauer spectroscopy on a series of Fe1-xCoxSi in the temperature range between 4 - 300K and also selected samples in applied external fields. Our data clearly show that there are indeed small ordered moments at iron in the concentration range between about x = 0.1 to 0.6 which are on the order of 0.2 uB.