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AM: Magnetismus

AM 21: Intermetallische Verbindungen, unterkühlte Metallschmelzen

AM 21.4: Vortrag

Donnerstag, 20. März 1997, 15:45–16:00, F5

Evolution of a metallic and magnetic state in (Fe,Mn)Si and Fe(Si,Ge) — •E. Bauer¹, R. Hauser¹, C. Reichl¹, G. Wiesinger¹, G. Zaussinger¹, M. Galli², and F. Marabelli² — ¹Institut für Experimentalphysik, Technische Universität Wien A - 1040 Wien, Austria — ²Dipartimento di Fisica ’A. Volta’, Universita di Pavia, I - 27100 Pavia, Italy

Although the narrow gap semiconductor FeSi was studied for many years, the ground state properties are not fully understood in detail. Various models like a two-level system with a non-magnetic ground state, spin fluctuations, Mott localisation or Kondo insulator behaviour were applied to account for the low temperature behaviour of this compound. Both the substitution of Fe by Mn and of Si by Ge drives the system towards a metallic state with long range magnetic order and a rather complicated helical spin structure.

By means of high field and high pressure studies performed on both series of alloys, the possibility of Kondo type interactions in concentrated 3d systems for alloys near to FeSi is discussed. At the verge of the transition from the non-magnetic to the magnetically ordered ground state, which can be forced by alloying or pressure, the possibility of a non-Fermi liquid is considered.