Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Poster Session: Correlated Electrons
TT 72.85: Poster
Mittwoch, 14. März 2018, 15:00–19:00, Poster B
Theoretical investigation of excitonic agnetism in LaSrCoO4 — •juan fernandez afonso, andrii sotnikov, and jan kunes — Institute of Solid State Physics TU Wien, Vienna, Austria
We use the LDA+U approach to search for possible ordered ground states of LaSrCoO4. We find a staggered arrangement of magnetic multipoles to be stable over a broad range of Co 3d interaction parameters. This ordered state can be described as a spin-density-wave-type condensate of dxy ⊗ dx2−y2 excitons carrying spin S=1. Further, we construct an effective strong-coupling model, calculate the exciton dispersion and investigate closing for the exciton gap, which marks the exciton condensation instability. Comparing the layered LaSrCoO4 with its pseudo cubic analog LaCoO3, we find that for the same interaction parameters the excitonic gap is smaller (possibly vanishing) in the layered cobaltite.