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arXiv · 1609.08358

Spin-wave dynamics in FeGe helimagnet: studied by small-angle neutron scattering

S. -A. Siegfried·A. S. Sukhanov·E. V. Altynbaev·D. Honnecker·A. Heinemann·A. V. Tsvyashchenko·S. V. Grigoriev
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Abstract

We have studied the spin-wave stiffness of the Dzyaloshinskii-Moriya helimagnet FeGe in a temperature range from 225~K up to $T_C \approx$~278.7~K by small-angle neutron scattering. The method we have used is based on [S. V. Grigoriev et al. Phys. Rev. B \textbf{92} 220415(R) (2015)] and was extended here for the application in polycrystalline samples. We confirm the validity of the anisotropic spin-wave dispersion for FeGe caused by the Dzyaloshinskii-Moriya interaction. We have shown that the spin-wave stiffness $A$ for FeGe helimagnet decreases with a temperature as $A(T) = 194(1-0.7(T/T_C)^{4.2})$ meVÅ$^2$. The finite value of the spin-wave stiffness $A = 58$ meVÅ$^2$ at $T_C$ classifies the order-disorder phase transition in FeGe as being the first order one.

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S. -A. Siegfried, A. S. Sukhanov, E. V. Altynbaev, D. Honnecker, A. Heinemann, A. V. Tsvyashchenko, S. V. Grigoriev. 2016-09-27. Spin-wave dynamics in FeGe helimagnet: studied by small-angle neutron scattering. https://doi.org/10.1103/physrevb.95.134415

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