Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 21: Magnetic Materials

MA 21.8: Vortrag

Mittwoch, 24. März 2010, 17:15–17:30, H23

Magnetic measurements on Tb₅Ge₃ — •Ariane Haase^1,2, Mathias Doerr², Marek Bartkowiak¹, Ramzy Daou^1,3, Yurii Skourski¹, Martin Rotter⁴, and Marc Uhlarz¹ — ¹Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf, 01314 Dresden — ²Institut für Festkörperphysik, TU Dresden, 01069 Dresden — ³Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden — ⁴University of Oxford, Department of Physics, Oxford OX1 3PU

Tb₅Ge₃ is a weak antiferromagnet, which orders at 83 K. It crystallizes in Mn₅Si₃-type hexagonal structure with two different positions for the Tb³⁺ ions. The hexagonal ab-plane is the easy plane of magnetization.

Magnetization and magnetostriction measurements have been done on a single crystal in static fields up to 30 T and in pulsed fields up to 50 T. In addition to the antiferromagnetic phase, three more phases were found in fields in the ab-plane at low temperatures. Surprisingly, the measurements along the b-axis do not resemble the a-axis properties which indicates an anisotropy in the hexagonal plane. Initial model calculations reveal the anisotropy of the magnetic exchange, which is dominant over the crystal electric field effect, as cause. The hard c-axis shows only one phase transition at 5 T followed by a nearly linear magnetization and magnetostriction slope which is attributed to a steady-going rotation of the moment.