Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 18: Spin Structures and Magnetic Phase Transitions
MA 18.1: Vortrag
Mittwoch, 25. März 2009, 10:15–10:30, HSZ 401
New ways of magnetoelastic measurements up to very high magnetic fields — •Mathias Doerr1, Ariane Haase2, Erik Kampert3, Martin Rotter4, Manuel Zschintzsch5, Yasuo Narumi6, and Michael Loewenhaupt1 — 1TU Dresden, Institut für Festkörperphysik — 2FZ Dresden-Rossendorf, Hochfeld-Magnetlabor — 3St. Radboud Universiteit Nijmegen, High Field Magnet Laboratory — 4University of Oxford, Clarendon Lab. — 5TU Dresden, Institut für Strukturphysik — 6University of Tokyo, ISSP
Scattering methods (x-rays or neutrons) as well as capacitive dilatometry can be used to investigate the magnetostriction (i.e. the change of length or shape) of solids with high accuracy and sensitivity (resolution limit for relative length changes about 10−9). The experimental range of scattering methods, especially, was extended to high magnetic fields of about 30 T in the last years. Therefore, these methods accompany the traditional dilatometry which was developed to work well up to the highest available fields (45 T in constant field magnets and 60 T in pulsed field systems). As examples, thermal expansion (investigated by x-ray diffraction and dilatometry), magnetostriction and magnetization measurements on the rare-earth based compounds Gd5Ge3, Tb5Ge3 and GdSi are discussed. The magnetoelastic behaviour of both Gd-containing substances shows an unexpected magnetic anisotropy which is caused by exchange striction effects. The complete set of (complementary) experimental methods resulted in a clear knowledge of the phase transitions from which, at least, the magnetic phase diagrams were constructed.