Evolution of helimagnetic correlations in Mn${}_{1-x}$Fe${}_x$Si with doping: a small-angle neutron scattering study

Abstract

We present a comprehensive small angle neutron scattering study of the doping dependence of the helimagnetic correlations in Mn${}_{1-x}$Fe${}_x$Si. The long-range helimagnetic order in Mn${}_{1-x}$Fe${}_x$Si is suppressed with increasing Fe content and disappears for $x$ $>$ $x^{\ast }$ $\approx$ 0.11, i.e. well before $x_C$ $\approx$ 0.17 where the transition temperature vanishes. For $x$ $>$ $x^{\ast }$, only finite isotropic helimagnetic correlations persist which bear similarities with the magnetic correlations found in the precursor phase of MnSi. Magnetic fields gradually suppress and partly align these short-ranged helimagnetic correlations along their direction through a complex magnetization process.