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 14.122: Poster
Dienstag, 25. März 2003, 15:15–19:15, Zelt
Magnetostriction of the ferromagnetic uranium compounds U3P4 and U3As4 — •Mathias Doerr1, Piotr Wisniewski2, Martin Rotter1, Michael Loewenhaupt1, and Zygmunt Henkie2 — 1Institute of Applied Physics (IAPD), University of Technology Dresden, D-01062 Dresden, Germany — 2Institute for Low Temperatures and Structure Research, Polish Academy od Science, Wrocław, Poland
The pnictides U3P4 and U3As4 show ferromagnetic order with fairly high Curie temperatures of 138 K and 198 K, respectively. They crystallize in a bcc structure (space group I43d) and are characterized by a strong hybridization of the 5f electrons with the conduction band. Despite the overall cubic symmetry, the local symmetry of the U-ion neighborhood is tetragonal. This structure leads to a strong crystalline ansiotropy.
Magnetostriction measurements at single crystals using a capacitive miniature dilatometer were performed at temperatures between 5 K and 220 K and in magnetic fields up to 15 T. The spontaneous magnetostriction due to the reorientation of the magnetic domains reaches rather high values: 8.10−4 for U3P4 and 4.2.10−4 for U3As4 for magnetic fields along the easy [111] direction. But, whereas the volume magnetostriction in U3P4 is nearly zero as expected the volume of U3As4 increases with field.The results may be understood using a distortion model that includes a rotation of the magnetic moments already in moderate fields.