Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Poster I

MA 16.42: Poster

Dienstag, 12. März 2013, 10:30–13:30, Poster D

Magnetic excitations in half- and overdoped manganites — Holger Ulbrich¹, •Thomas Bardenheuer¹, Paul Steffens², Yvan Sidis³, Daniel Lamago³, and Markus Braden¹ — ¹II. Physikalisches Institut, Universität zu Köln, 50937 Köln — ²Institut Laue Langevin, Grenoble — ³Laboratoire Léon Briilouin, CE Saclay, Gif sur Yvette Cedex

Magnetic excitations were studied by inelastic neutron scattering on various manganites that exhibit charge, orbital and spin ordering. At half-doping the magnetic excitation spectra can be perfectly modelled by a simple Heisenberg model of magnetic interaction which perfectly agrees with the Goodenough scenario of charge and orbital ordering. There seems to be no qualitative difference in all the half-doped manganites studies so far irrespective of their layered or three-dimensional character. For higher doping we observe a stripe-like arrangement of the electronic and magnetic ordering. Furthermore the magnetic excitation spectra closely resemble the hour-glass like dispersion observed in many high-temperature superconducting cuprates. Besides a large ratio of intra- to inter-stripe magnetic inteaction parameters, a short range of the magnetic ordering perpendicular to the stripes can be identified as decisive parameter to induce a hour-glass dispersion in insulating stripe phases.

[1] H. Ulbrich et al., Phys. Rev. Lett. 106, 157201 (2011) [2] H. Ulbrich, Phys. Rev. B 84, 094453 (2011) [2] H. Ulbrich, Phys. Rev. Lett. 108, 247209 (2012)