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MA: Magnetismus

MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)

MA 13.102: Poster

Dienstag, 9. März 2004, 15:00–19:00, Bereich A

Critical small angle scattering of polarised neutrons in MnSi — •Robert Georgii¹, Peter Böni¹, Daniel Lamago¹, Sergey Grigoriev², Sergey Maleyev², Alexey Okorokov², Helmut Eckerlebe³, Klaus Pranzas³, and Bertrand Roessli⁴ — ¹Technische Universität München, 85747 Garching, Germany — ²Petersburg Nuclear Physics Institute, Gatchina, St.Petersburg 188300, Russia — ³GKSS Forschungszentrum, 21502 Geesthacht, Germany — ⁴Laboratory for Neutron Scattering, ETH & PSI, 5232 Villigen, Switzerland

The chiral fluctuations in the weak itinerant magnet MnSi have been studied by means of polarised neutron scattering. Because of a lack of a centre of symmetry the magnetic moments are arranged along a left-handed spiral due to the Dzyaloshinskii-Moriya interaction. Therefore, the chiral fluctuations can be investigated without the need of application of a magnetic field. The experiments show that the incommensurate magnetic peaks evolve with increasing temperature into diffuse scattering that is mainly concentrated in spheres around the nuclear Bragg peaks. The scattering is fully polarised for q ∥ P₀ and is depolarised for q ⊥ P₀. This manifests the purely chiral nature of the scattering. From these data we have determined the critical exponents of the correlation length of the chiral fluctuations.