Magnetic excitations in helimagnets over a broad range of spin-spiral pitch lengths.

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The aim of the proposed project is to understand the low-energy spin dynamics of helimagnon excitations in chiral magnetic materials exhibiting spin-spiral or skyrmion order. We will investigate several compounds characterized by very different pitches of the spin helix or, if viewed in the reciprocal space, by different incommensurability parameters that are either longer and shorter with respect to the previously studied reference compound MnSi. On the one hand, noncollinear magnets that are typically measured by standard neutron diffraction possess relatively short periods of the spiral structure on the order of several interatomic distances, as in the case of Sr3Fe2O7 or ZnCr2Se4. On the other hand, long-pitch helical structures typical for skyrmion-lattice systems, such as B20 compounds or Cu2OSeO3, fall in the applicability range of small-angle neutron scattering instruments. Our results are expected to span the broad range of spin structures between these two extremes and extend to new materials with possibly even longer helix pitches.