Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 12: Correlated Electrons - Spin Systems and Itinerant Magnets: Experiment
TT 12.4: Vortrag
Samstag, 5. März 2005, 11:30–11:45, TU H2053
Weak Itinerant Ferromagnetism and Half-Metallic State among Filled Skutterudites: MFe4Sb12 (M = Na, K, Ca, Ba) — •A. Leithe-Jasper, W. Schnelle, H. Rosner, M. Baenitz, A. Rabis, A.A. Gippius, E.N. Morozova, J.A. Mydosh, and Y. Grin — Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany
The chemical, structural and magnetic properties of alkali and alkaline-earth metal compounds with filled-skutterudite structure, MFe4Sb12 (M = Na, K, Ca, Ba), are described [1,2]. X-ray and neutron diffraction and elemental analysis established the crystal structure without defects and disorder on the cation site. The electronic structure is calculated by LMTO and FPLO methods. Quantum chemical calculations (electron localization function, ELF) reveal the covalent character of both Fe–Sb and Sb–Sb interactions. Electronic structure calculations within the LDA exhibit a band ferromagnetic ground state and predict a half-metallic behaviour for M = Na, K. In contrast to Ca/BaFe4Sb12, the alkali-metal skutterudites are itinerant electron ferromagnets with small magnetic moments (≈ 0.25 µB/Fe atom) and TC ≈ 85 K. Yet, the paramagnetic moments of all four compounds are between 1.5 and 1.7 µB per Fe atom, indicating similar Stoner-factors.
[1] A. Leithe-Jasper et al. Phys. Rev. Lett. 91, 037208 (2003).
[2] A. Leithe-Jasper et al. Phys. Rev. B, in print (1 Dec 2004).