Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.109: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Specific heat, thermal conductivity and thermoelectric power of NaFe₄Sb₁₂, KFe₄Sb₁₂ and BaFe₄Sb₁₂ — •Narayani Senthilkumaran¹, Michael Baenitz¹, Andreas Leithe-Jasper¹, Walter Schnelle¹, Annegrit Rabis¹, Andrei Gippius^1,2, Yuri Grin¹, and Frank Steglich¹ — ¹MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D-01187, Dresden, Germany — ²Moscow State University, Faculty of Physics, Moscow, Russia

The newly synthesized alkali metal iron antimonides with a filled skutterudite structure, NaFe₄Sb₁₂ and KFe₄Sb₁₂ together with the known BaFe₄Sb₁₂ have been investigated by means of specific heat and thermal transport measurements. Measurements of specific heat confirm ferromagnetism with a T_C around 85 K for NaFe₄Sb₁₂ whereas for BaFe₄Sb₁₂ no signs of magnetic order are observed. The specific heat is analysed in terms of lattice, electronic and magnetic contributions. Furthermore relatively high values of γ (∼ 100 mJ/mol K²) are discussed in the context of high density of states N(E_F), obtained from the band structure calculations. Using BaFe₄Sb₁₂ as a phonon reference, the magnetic contribution to the specific heat C_m(T) of NaFe₄Sb₁₂ has been estimated. C_m(T) shows an additional anomaly around 30 K, that could be magnetic (metamagnetic transition) or dynamic (locking-in transition of the rattlers) in origin. The thermal transport properties are compared with that of other well known compounds with filled skutterudite structure from the literature. The thermal conductivity has been analysed taking into account boundary scattering, Umklapp process, defect, electron and resonant scattering.