Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 45: Correlated Electrons: Poster Session
TT 45.26: Poster
Donnerstag, 29. März 2012, 15:00–19:00, Poster B
Spin structure of Fe- and Co-substituted MnSi and MnGe — •Sven-Arne Siegfried1, Dirk Menzel1, Sergey Grigoriev2, Vadim Dyadkin2, Nadezhda Potapova2, Evgeny Moskvin2, Anatoly V. Tsvyashchenko3, Mathias Kraken1, and Jochen Litterst1 — 1IPKM, TU Braunschweig, Germany — 2PNPI, Gatchina, Russia — 3IHPP, Troitsk, Russia
The intriguing magnetic and transport properties of the transition metal-monosilicides TM-Si (TM = Mn, Fe, Co) have been studied extensively during the last thirty years, whereas the properties of the TM-monogermanides are much less investigated due to the complexity of the synthesis. Both systems order in a helical spin structure which can be transformed by a magnetic field into a conical and even a parallel configuration. Close to the ordering temperature a skyrmionic A-phase exists. SQUID magnetization and Mössbauer-spectroscopic measurements on Mn1−xCoxSi and Mn1−xFexSi have been performed to determine the magnetic phase diagrams. For a critical substitution of Co (xCo ≈ 0.08) and Fe (xFe ≈ 0.15) the ferromagnetic order in MnSi is suppressed. The intermixing compound Mn1−xFexGe has been magnetically characterized for the first time. A preliminary magnetic phase diagram for different Fe-concentrations has been created. Small angle neutron scattering has been used to determine the spin structure of this compound. The monogermanides show a remarkably huge increase of the helix period from 3 nm for MnGe up to 70 nm for FeGe compared to 18 nm for MnSi, and the critical fields HC1 and HC2 increase from MnGe towards FeGe by the factor of 10.