Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 14: Spin Systems and Itinerant Magnets
TT 14.11: Vortrag
Dienstag, 27. März 2007, 17:00–17:15, H19
Ordering and spin waves in vanadium spinels — •Natalia Perkins1 and Olga Sikora2 — 1Technische University of Braunschweig, Braunschweig, Mendellsohnstrasse 3,38106, Germany — 2Max Planck Institute for Complex System, Noethnitzer Str.38, Dresden, 01187, Germany
We consider the effect of quantum spin fluctuation on the ground state properties of spin-orbital Hamiltonian on a pyrochlore lattice, which is derived to model the ground state properties of vanadium spinel oxides AV2O4 (A=Zn, Mg, Cd). As the magnitude of the spin-orbit interaction and that of the exchange one are very similar, both interactions should be simultaneously considered. We show that the low-energy effective Hamiltonian decides about the magnetic interactions of the system and determines the ground state. We also find that the magnetic excitation spectrum obtained by linear spin-wave approach in case of quenched orbital angular momentum differs significantly from one calculated in the magnetic exciton model formulated for the case with unquenched orbital angular momentum. Thus we suggest that the performance of the neutron scattering experiment would help to clarify both the overall picture of the ground state and of the excitation spectrum.