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TT: Tiefe Temperaturen
TT 3: Schwere Fermionen
TT 3.9: Talk
Monday, March 26, 2001, 11:45–12:00, A
Structure and magnetic order in Fe2+xVxAl — •I. Maksimov1, D. Baabe1, H.-H. Klauß1, F.J. Litterst1, R. Feyerherm2, D. Többens2, A. Matsushita3, and S. Süllow1 — 1Institut für Metallphysik und Nukleare Festkörperphysik, TU Braunschweig, Germany — 2HMI GmbH, Berlin, Germany — 3National Research Institute for Metals, Tsukuba, Japan
”Kondo–insulating like” Fe2VAl exhibits a strong sample
dependence: quenched material is semiconducting and paramagnetic,
slowly–cooled samples show almost metallic transport and
ferromagnetism below TC ∼ 13 K. To determine the
cause of this sample dependence we executed high resolution
neutron diffraction experiments on Fe2+xVxAl
(0 ≤ x ≤ 0.5). In particular, we studied
slowly–cooled magnetic and quenched non–magnetic Fe2VAl.
Our experiments establish that quenched Fe2VAl contains a
significant level (6%) of Al deficiency. The Al deficiency is
reflected in a smaller unit cell volume of quenched Fe2VAl
compared to slowly cooled material, indicating that chemical
pressure leads to the suppression of ferromagnetism in the former
sample. Our results suggest that the transport properties of
quenched Fe2VAl are strongly affected by the deficiency
disorder. µ+SR experiments on slowly cooled Fe2VAl
reveal the presence of magnetic fluctuations at temperatures up
to 6TC. These results will be discussed in context with
available Mössbauer–spectroscopy data.
Supported by the DFG under grant no SU 229/4-1.