Dresden 2020 – wissenschaftliches Programm
Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...
TT 63.5: Vortrag
Donnerstag, 19. März 2020, 16:15–16:30, HSZ 304
Multi band modelling of exchange couplings in edge-sharing Cu-O chains — •Dijana Milosavljevic1, Oleg Janson2, Jan Tomczak3, and Helge Rosner1 — 1Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden — 2IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany — 3Technical University of Vienna, Austria
One of the structural features that has a crucial role in the determination of the exchange coupling constant in chain containing compound is the Cu-O-Cu bond angle. However the angle is not the only factor. Equally important influence on the exchange coupling has the presence of the side groups coupled to the O-ligands. To demonstrate this we show two representatives of edge sharing chain cuprates with similar Cu-O-Cu bond angles but drastically different exchanges. From detailed DFT studies and subsequently derived multi band tight binding models we find that the crucial parameter is the difference in onsite energies of ligand O 2px and O 2py orbitals parallel and perpendicular to the Cu-O chain. Using this parameter, a microscopic explanation for the drastically different magnetic exchanges can be established. To illustrate the crucial influence of side groups we provide examples of H-containing compounds where a rotation of H even leads to a sign change of the superexchange interaction from strongly ferromagnetic to strongly antiferromagnetic.