Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 38: Correlated Electrons: Spin Systems and Itinerant Magnets 1

TT 38.3: Vortrag

Donnerstag, 29. März 2012, 10:00–10:15, H 3010

Magnetic excitations in disordered striped antiferromagnetic insulators — •Eric Andrade and Matthias Vojta — Technische Universität Dresden

The compounds of the La_2−xSr_xCoO₄ series are isostructural to the 214 family of cuprate superconductors, but nevertheless remain insulating over a wide range of doping. Recently, it was observed that the x=1/3 compound displays a peculiar type of magnetism, with short-ranged static antiferromagnetic order and an hour-glass-like magnetic excitation spectrum, which can be directly associated with the presence of stripe order. Here we argue that inhomogeneities, coming from deviations of perfectly ordered stripes, are of central importance and, by calculating the magnetic excitation spectrum, we show that a scenario of disordered charge stripes (formed by Co²⁺ and Co³⁺ ions) is consistent with the experimental data.