Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.68: Poster

Samstag, 5. März 2005, 11:00–16:30, Poster TU C

Itinerant electron metamagnetism and weak ferromagnetism in LaCo₉Si₄ and YCo₉Si₄ — •H. Michor¹, S. Özcan¹, M. El-Hagary¹, E. Bauer¹, M. Reissner¹, G. Hilscher¹, S. Khmelevskyi², P. Mohn², P. Rogl³, and H. Rosner⁴ — ¹Institut für Festkörperphysik, T.U. Wien, A-1040 Wien, Austria — ²Center for Computational Materials Science, T.U. Wien, Austria — ³Institut für Physikalische Chemie, Universität Wien, Austria — ⁴Max-Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany

LaCo₉Si₄ is a strongly exchange enhanced Pauli paramagnet with an instability towards weak ferromagnetism, i.e. exhibits itinerant electron metamagnetism at about 3.5 T for H||c and 6 T for H⊥ c, which is the lowest value ever found for rare earth intermetallic compounds [1]. Despite of the smaller unit cell volume isostructural and isoelectronic YCo₉Si₄ exhibits a weak itinerant ferromagnetic ground state (T_C≃ 25 K) already in zero-field. The ground state properties of La- and YCo₉Si₄ are discussed on basis of magnetisation, specific heat, and resistivity measurements and via ab-initio electronic structure calculations. The band structure calculations result in a ferromagnetic groundstate for both compounds with moments substantialy larger than the experimentally observed moments. The origin of these discrepancies is briefly discussed. [1] H. Michor et al., Phys.Rev. B 69 (2004) 081404(R).