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 14.114: Poster
Dienstag, 25. März 2003, 15:15–19:15, Zelt
NaFe4Sb12-Magnetic Resonance studies — •Annegrit Rabis1, Andrei Gippius1,2, Elena Morozowa1,2, Michael Baenitz1, Andeas Leithe-Jasper1, Walter Schnelle1, Narayani Senthilkumaran1, Frank Steglich1, and Yuri Grin1 — 1MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D-01187 Dresden, Germany — 2Moscow State University, Faculty of Physics, Moscow, Russia
The new alkali metal iron antimonide compound NaFe4Sb12 with a filled skutterudite structure was investigated by means of 23Na NMR as well as 121,123Sb NQR spectroscopy in the temperature range from 4 K to 290 K. At about 85 K the material becomes ferromagnetically ordered. Only one sodium position was detected in the 23Na NMR spectrum according to the crystal structure. The temperature dependence of the Knight-shift K shows a fast decrease below the transition temperature. From K–χ plot we observed three linear regimes corresponding to three different hyperfine coupling constants. The values of these hyperfine constants are in line with small magnetic moments of iron found in magnetization measurements. A large displacement parameter detected from X-ray diffraction gives a strong evidence that the sodium atom rattles in the antimony cage. This is supported by small line widths in the spectra at higher temperatures as well as in the MAS spectra. The antimony NQR spectrum measured at 300 K consists of five lines which were assigned to two NQR transition lines for the 121Sb (I = 5/2) and three lines for the 123Sb (I = 7/2) isotopes with asymmetry parameter η = 0.45. This assignment confirms the existence of only one crystallographic site in the framework of antimony with essentialy non-axial symmetry.