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MA: Fachverband Magnetismus
MA 11: Posters Magnetism III
MA 11.11: Poster
Wednesday, September 29, 2021, 13:30–16:30, P
Dipolar interactions and spin dynamics in the itinerant ferromagnets Fe and Ni — •Lukas Beddrich1,2, Steffen Säubert3,4, Johanna K. Jochum1, Christian Franz1,5, and Peter Böni2 — 1Research Neutron Source Heinz Maier-Leibnitz (FRM II) | TU München — 2Physics Department | TU München — 3Chair for Topology of Correlated Systems (E51) | Physics Department | TU München — 4Department of Physics | Colorado State University — 5Jülich Center for Neutron Science (JCNS)
The spin wave dispersion of an isotropic ferromagnet is comprehensively described by the Holstein-Primakoff theory, which takes dipolar interactions into account. The dispersion follows a quadratic form for large q values ESW∝ q2, whereas for small q the dispersion shows linear behavior. This is attributed to the long-range dipolar interaction between the magnetic moments. The subtle influence of these interactions on the magnon spectrum are expressed by the dipolar wave vector qD. The dipolar interactions are primarily probed for q ≤ qD. Utilizing the modern MIEZE method, a neutron resonance spin echo technique, we investigated the spin wave dispersion in iron and the paramagnetic spin fluctuations in nickel at small momentum and energy transfer with high resolution, never achieved before by neutron scattering. The results show excellent agreement with previously conducted triple-axis measurements by Collins et al. in the overlapping q regime, while extending the investigated range of the spin wave dispersion down to a momentum transfer of q=0.015 A−1 with unprecedented energy resolution.