Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.25: Poster
Mittwoch, 13. März 2013, 15:00–19:00, Poster D
Synthesis and characterization of single-layered manganites — •Johannes Engelmayer, Oliver Breunig, Holger Ulbrich, Markus Braden, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Germany
Single-layered manganites show a complex interplay between charge, orbital, and magnetic degrees of freedom. For La1−xSr1+xMnO4 and Pr1−xCa1+xMnO4 with doping level x=0.5 (half-doping), the Goodenough model is well established. This model proposes a site-centered charge order with a checkerboard pattern of Mn3+ and Mn4+ ions that is accompanied by an orbital order. This charge and orbital order induces a magnetic order with ferromagnetic three-spin zig-zag chains and antiferromagnetic interchain coupling. For Pr1−xCa1+xMnO4 and Nd1−xSr1+xMnO4 with x=2/3, four-spin zig-zag chains could be observed due to a 2:1 ratio of Mn4+ and Mn3+. In order to study the charge, orbital, and magnetic order in manganites with other dopants, single crystals of Pr1−xSr1+xMnO4 and Nd1−xCa1+xMnO4 with 0.5≤ x≤ 0.75 were grown and their structural parameters were determined. We present measurements of resistivity, magnetization, and specific heat that show indications for charge order around room temperature. A dopant and doping-level dependence of the ordering temperature is discussed.
Supported by the DFG through SFB 608.