Spin waves in full-polarized state of Dzyaloshinskii-Moriya helimagnets: Small-angle neutron scattering study.

Authors:
S. V. Grigoriev, A. S. Sukhanov, E. V. Altynbaev, S.-A. Siegfried, A. Heinemann, P. Kizhe, and S. V. Maleyev
The year of the publication:
2015
Journal:
Phys. Rev. B vol. 92 220415(R)
Abstract:

We develop the technique to study the spin wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centred at the momentum transfer corresponding to the helix wave vector in helimagnetic phase $k_s$, which is oriented along the applied magnetic field ${\bf H}$. The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness $A$ for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature $T_c$.

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