Small-angle neutron scattering in the fully polarized phase of noncollinear magnets with interfacial-like Dzyaloshinskii-Moriya interaction

Abstract

Spin waves in non-collinear magnets with $C_{nv}$ symmetry are discussed in the context of inelastic neutron scattering in small-angle scattering geometry. In the framework of minimal model including exchange coupling, Dzayloshinskii-Moriya interaction (DMI) and single-ion anisotropy, we consider the system properties at moderate external fields and in the high-field fully polarized phase. In the latter case, the magnon spectrum is gapped and non-reciprocal due to DMI with the minimum perpendicular to the field direction for in-plane field and is ferromagnetic-like for the field along the high-symmetry axis. Inelastic small-angle neutron scattering in the fully polarized phase (SWSANS) is considered in four different geometries. It is shown that analysis of field dependence of the SWSANS cutoff feature in these geometries allows determining all important parameters of the model. Possibility of the proposed method utilization in thin films with interfacial DMI is also discussed.