Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 55: Poster II

MA 55.51: Poster

Freitag, 4. April 2014, 10:30–13:30, P2

Critical magnetic fluctuations in Heisenberg antiferromagnets — •Kuo Feng Tseng¹, Andrew Walters¹, Thomas Keller^1,2, Sibel Bayrakci¹, and Bernhard Keimer¹ — ¹Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — ²Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II), D-85747 Garching, Germany

We have performed elastic and inelastic neutron scattering measurements in classical Heisenberg antiferromagnets MnF₂ (3D) and Rb₂MnF₄ (2D) with a Néel temperature T_N of 67.4 and 38.4 K respectively. We utilized high resolution spin-echo and Larmor diffraction techniques at the TRIple axis resonance SPin echo spectrometer (TRISP). By appropriately choosing field geometries at TRISP, we are able to separate the longitudinal and transverse correlations of the critical fluctuations close to T_N with the advantages of neutron ray-tracing method. Determinations of the longitudinal and transverse linewidths (=inverse lifetime) on MnF₂ and Rb₂MnF₄ were obtained at TRISP with extremely high resolution in a micronelectron-volt range. The results and technique open up a new avenue for a re-investigation of underlying physics in the critical phenomena.