Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-wave dynamics in FeGe helimagnet: studied by small-angle neutron
  scattering   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 $A(T) =
194(1-0.7(T/T_C)^{4.2})$ meV\AA$^2$. The finite value of the spin-wave
stiffness $A = 58$ meV\AA$^2$ at $T_C$ classifies the order-disorder phase
transition in FeGe as being the first order one.

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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: econ
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
3
The categories of this paper are: physics
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The categories of this paper are: math-ph
37
The categories of this paper are: supr-con