Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.7: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

Interplay between structural disorder and magnetic susceptibility in FeSi — •Tommy Reimann, Dirk Menzel, Dirk Schulze Grachtrup, and Joachim Schoenes — Institut für Physik der Kondensierten Materie, TU Braunschweig, Germany

The narrow gap semiconductor FeSi has been of high experimental and theoretical interest for over 60 years, mostly due to its unusual magnetic behavior. To clarify the reasons for the Curie-Weiss-like reincreasing of the magnetic susceptibility at low temperatures, we performed transport and susceptibility measurements on different FeSi single crystals grown via the tri-arc Czochralski method. A part of the FeSi samples, which were grown with slightly different stoichiometry close to 1:1 were annealed at 1000^∘C for 3 months. The susceptibility measurements reveal a reduction of the Curie-constant due to the annealing process. In addition, samples with iron excess show a smaller residual susceptibility compared to crystals with iron deficit. This fact cannot be explained by the often claimed assumption that uncompensated iron carries the magnetic moment. The observed appearance of variable range hopping conductivity in combination with a negative magnetoresistivity suggests that Anderson-localized electrons caused by structural disorder induce the low temperature Curie-Weiss-like behavior.