Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 12: Correlated Electrons - Spin Systems and Itinerant Magnets: Experiment

TT 12.4: Talk

Saturday, March 5, 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 µ_B/Fe atom) and T_C ≈ 85 K. Yet, the paramagnetic moments of all four compounds are between 1.5 and 1.7 µ_B 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).