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Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: CE: Low-dimensional Systems - Materials 1

TT 18.3: Vortrag

Montag, 14. März 2011, 19:00–19:15, HSZ 201

Ferromagnetic versus helical order in edge sharing CuO2 chains - a computational study — •Helge Rosner1, Ulrike Nitzsche2, Roman Kuzian2, and Stefan-Ludwig Drechsler21MPI CPfS Dresden — 2IFW Dresden

The magnetic ground state of edge sharing CuO2 spin 1/2 Heisenberg chains with ferromagnetic nearest neighbor exchange J1 and antiferromagnetic second neighbor exchange J2 depends delicately on structural details of the crystal structure, like Cu-O-Cu bond angles, Cu-O distances and the position of the cations. Without taking into account a renormalization by the interchain coupling, a critical ratio α=−J2/J1=1/4 separates a ferromagnetic from a helical ground state (FM for α < 1/4, helical for α > 1/4). Here, we present a density functional based band structure study that investigates the different influences of various structural parameters for Li2CuO2 as example compound. We find that the ferromagnetic and antiferromagnetic contributions develop rather differently for the same structural changes. Therefore, the key parameter α for the ground state is especially sensitive to small structural changes that might be induced by temperature or pressure variation.

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