Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)
MA 13.101: Poster
Dienstag, 9. März 2004, 15:00–19:00, Bereich A
Discrepancy between local and global structure in magnetically frustrated ZnV2O4 — •P. Pfalzer, M. Preisinger, M. Klemm, and S. Horn — Universität Augsburg, Experimentalphysik II, Universitätsstr. 1, 86135 Augsburg
Development of unusual magnetic properties like spin fluctuations down to lowest temperatures have aroused interest in geometrically frustrated magnets. Among these are the cubic spinel system LiV2O4, the first transition-metal oxide to show heavy fermion behavior, and the isostructural system ZnV2O4. For the latter compound a symmetry breaking structural phase transition was reported for polycrystalline material, presumably lifting this degeneracy, followed by a transition into an antiferromagnetic state. In single crystals, however, this structural transition is suppressed and a spin-glass-like ground state develops. To clarify whether local structural distortions or fluctuations play a role in the formation of this low temperature behavior, we have performed EXAFS measurements on single crystals of ZnV2O4 as well as on various powder samples. We have shown that the cubic symmetry expected from XRD is broken on a local scale in single crystals of ZnV2O4. In particular the octahedral oxygen neighborhood of the vanadium ions is distorted leading to the formation of two nonequivalent oxygen sites.