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TT: Tiefe Temperaturen

TT 34: Correlated Electrons: Spin Systems and Itinerant Magnets

TT 34.6: Vortrag

Freitag, 31. März 2006, 11:30–11:45, HSZ 301

Itinerant iron magnetism and high spin polarization in filled skutterudites — •Helge Rosner, Andreas Leithe-Jasper, Walter Schnelle, Joerg Sichelschmidt, Steffen Wirth, John Mydosh, and Yuri Grin — MPI CPfS Dresden

Compounds with the filled skutterudite structure are currently under intensive investigation due to their wide spectrum of ground state properties. Here, we report a combined theoretical and experimental study of the electronic and magnetic properties of the compound family AFe₄Sb₁₂ (A=Na,K,Ca,Ba,Yb) by means of band structure calculations and measurements of point-contact Andreev reflections, optical spectra and thermodynamic properties (χ, C_P, ρ). Whereas the compounds with A=Na,K order ferromagnetically [1] with a high transport spin polarisation P_t ∼ 67% [2], the magnetic order for A=Ca,Ba,Yb is suppressed by strong spin fluctuations. The latter compounds show a metamagnetic transition in high magnetic fields as suggested by fixed spin moment calculations. The Yb compound, formerly considered as a heavy fermion system, is proven to be in a stable divalent state by band structure calculations and optical and thermodynamic data [3].

[1] A. Leithe Jasper et al. Phys. Rev. Lett. 91, 037208 (2003).

[2] G. Sheet et al. Phys. Rev. B 72, in print (2005).

[3] W. Schnelle et al. Phys. Rev. B 72, 020402(R) (2005).