Regensburg 2000 – wissenschaftliches Programm

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AM: Magnetismus

AM 13: Postersitzung: Dünne Schichten (1–22), Magnetowiderstand (23–40), Phasenübergänge (41–55), Mikromagnetismus (56–68), Spektroskopie (69–77), Nanokristalline Materialien (78–82), Anisotropie (83–86), Schmelzen (87–90), Weitere Bereiche (91–100)

AM 13.83: Poster

Dienstag, 28. März 2000, 16:00–20:00, A

Neutron-diffraction study of UNiGe in high-magnetic fields up to 17 T — •Karel Prokes¹, Oleksandr Chernyavski², Pavel Svoboda², Vladimir Sechovsky², Ekkehard Bruck³, Frank de Boer³, Michael Meissner¹, and Peter Smeibidl¹ — ¹Hahn-Meitner-Inst., Glienickerstr. 100, 141 09 Berlin — ²DES, Charles University, 121 16 Prague, The Czech Republic — ³Van der Waals-Zeeman Inst., University of Amsterdam, 1018 XE Amsterdam, The Netherlands

UNiGe orders antiferromagnetically below TN = 50 K with an additional magnetic phase transition at 42 K. Both structures are non-collinear with significant a-axis component and can be modified by application of a magnetic field along the b or c axes. While the magnetic structure above the highest critical field is forced ferromagnetic for both field orientations, in the intermediate region uncompensated antiferromagnetic structures exist. The a-axis is a hard magnetization direction. Our recent neutron-diffraction experiments in high magnetic fields up to 17 T directed along the principal axes are entirely in agreement with the proposed high magnetic anisotropy of UNiGe. Energy considerations suggest that the antiferromagnetically aligned x-component of the magnetization should prevail in the forced ferromagnetic state. Qualitatively, this can be understood as inability of the Zeeman energy to overcome the anisotropic exchange.