Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 66: Magnetic Heusler Materials, Semimetals und Oxides
(Joint session of MA and TT organized by MA)
TT 66.11: Vortrag
Donnerstag, 10. März 2016, 12:15–12:30, H34
Competing Superexchange Interactions in Sr2-xCaxCoOsO6 Double Perovskite Osmates — •Ryan Morrow1, 2, Rohan Mishra1, Oscar D. Restrepo1, Molly R. Ball1, Wolfgang Windl1, Sabine Wurmehl2, 3, Ulrike Stockert2, 3, Bernd Büchner2, 3, Jiaqiang Yan4, Michael A. McGuire4, John W. Freeland5, Daniel Haskel5, and Patrick M. Woodward1 — 1OSU, Columbus, OH, United States — 2IFW, Dresden, Germany — 3TUD, Dresden, Germany — 4ORNL, Oak Ridge, TN, United States — 5ANL, Argonne, IL, United States
Double perovskites containing mixed transition metal cations have exhibited numerous desirable properties such as colossal magnetoresistance, half metallic transport, and high temperature ferrimagnetism. However, a predictive understanding of the superexchange mechanisms which control the magnetism of these materials when they are insulating and contained ordered 3d and 4d or 5d transition metals has remained elusive. In this work, the novel insulators Sr2CoOsO6, SrCaCoOsO6, and Ca2CoOsO6 are studied through a combination of AC and DC magnetometry, specific heat, X-ray magnetic circular dichroism, and neutron powder diffraction in order to characterize two antiferromagnetic orders in Sr2CoOsO6, two spin glass transitions in SrCaCoOsO6, and ferrimagnetic ordering in Ca2CoOsO6. The details of the crystal structures will be used to draw connections between the tuning of bonding geometry through chemical pressure and the competition between short and long range superexchange interactions on the resulting magnetic ground states.