Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 22: Low-Dimensional Systems: Charge Order
TT 22.5: Vortrag
Montag, 31. März 2014, 16:00–16:15, BEY 81
Doping dependence of charge order in single-layered manganites R1−xA1+xMnO4 — •Johannes Engelmayer, 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 half-doped (x=0.5) La1−xSr1+xMnO4 and Pr1−xCa1+xMnO4 the so-called 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 x>0.5 zig-zag chains with larger step size have been reported in Pr1−xCa1+xMnO4 and Nd1−xSr1+xMnO4, e.g. four-spin zig-zag chains arise for x=2/3 due to a 2:1 ratio of Mn4+ and Mn3+ [1]. In order to study the effect of different dopants on the ordering temperature, single crystals of Pr1−xSr1+xMnO4, Nd1−xCa1+xMnO4 and Nd1−xSr1+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 features associated with charge order. The dependence of the ordering temperature on the dopants and the doping level is discussed.
Supported by the DFG through SFB 608
H. Ulbrich, M. Braden, Physica C 481, 31 (2012)