Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.69: Poster

Samstag, 5. März 2005, 11:00–16:30, Poster TU C

Magnetic Ordering in Trigonal Chain Compounds — •Christian Laschinger¹, Udo Schwingenschlögl¹, Volker Eyert¹, Thilo Kopp¹, Raymond Frésard², and Ulrich Eckern¹ — ¹University of Augsburg — ²Institut des Sciences de la Matière et du Rayonnement, Caen, France

We investigate the microscopic origin of the ferromagnetic and antiferromagnetic spin exchange couplings in the quasi-one-dimensional cobalt compounds Ca₃ABO₆ with A = Fe, Co and B = Co, Rh. From electronic structure calculations we find A 3d low spin and high spin states alternating along the characteristic chains. In addition strong d-p hybridisation leads to the formation of extended localized magnetic moments centered at the high spin sites. Antiferromagnetic coupling along the chains is induced by a strong metal-metal overlap via the d_3z²−r² orbitals of the low spin sites. It competes with ferromagnetic exchange, which originates in a cyclic exchange through the ligand atoms.