%0 journal article
%@ 1098-0121
%A Grigoriev, S.V., Siegfried, S.-A., Altynbayev, E.V., Potapova, N.M., Dyadkin, V., Moskvin, E.V., Menzel, D., Heinemann, A., Axenov, S.N., Fomicheva, L.N., Tsvyashchenko, A.V.

%D 2014
%J Physical Review  B
%N 17
%P 174414 
%R doi:10.1103/PhysRevB.90.174414
%T Flip of spin helix chirality and ferromagnetic state in Fe 1−x Co x Ge  compounds
%U https://doi.org/10.1103/PhysRevB.90.174414
17 
%X We have synthesized the solid solutions of Fe 1−x Co x Ge  compounds with x  running from 0.0 to 0.9. Small-angle neutron scattering and magnetization measurements have shown that these compounds are ordered into the spin helix structure below the critical temperature T c  . The helix is transformed into the ferromagnet by application of the magnetic field above the critical value H c2  . It is shown that T c   decreases smoothly with concentration x  from 280 K for FeGe to 0 for CoGe. The values of the helix wave vector k s   and the critical field H c2   depend strongly on concentration x , firstly, decreasing from pure FeGe to its minimum (|k s |→0 , H c2 →0 ) at x c ≈0.6 , and, then increasing again at higher x . Thus, we observe a transformation of the helix structure to the ferromagnet at x→x c   at zero field. We concluded that this transformation is caused by different signs of the spin helicity for the compounds with x>x c   and x<x c  . We believe that the mechanism of the transformation is caused by the competition between the Dzyaloshinskii-Moriya interaction and the cubic anisotropy.