Magnetic susceptibility measurements have shown that the compounds Mn(1-x)Fe(x)Ge are magnetically ordered through the whole range of concentrations x = [0.0,1.0]. Small-angle neutron scattering reveals the helical nature of the spin structure with a wave vector, which changes from its maximum (|k| = 2.3 nm(-1)) for pure MnGe, through its minimum (|k| → 0) at x(c) ≈ 0.75, to the value of |k| = 0.09 nm(-1) for pure FeGe. The macroscopic magnetic measurements confirm the ferromagnetic nature of the compound with x = x(c). The observed transformation of the helix structure to the ferromagnet at x = x(c) is explained by different signs of chirality for the compounds with x > x(c) and x

No abstract

No abstract

No abstract

Monosilicides of 3d-metals frequently show a chiral magnetic ordering with the absolute configuration defined by the chirality of the crystal structure and the sign of the Dzyaloshinskii-Moriya interaction (DMI). Structural and magnetic chiralities are probed here for Fe1−xCoxSi series and their mutual relationship is found to be dependent on the chemical composition. The chirality of crystal structure was previously shown to be governed by crystal growth, and the value of the DMI is nearly the same for all monosilicides of Fe, Co and Mn. Our findings indicate that the sign of the DMI in Fe1−xCoxSi is controlled by the Co composition x. We have been able to directly measure the change of the link between structure and magnetism in this helimagnetic B20 alloy.PACS numbers: 61.12.Ex, Scattering of polarized neutrons on chiral magnetic structures allows one to determine the absolute magnetic configuration, thus left-and right-handed helices can be easily distinguished [1]. On the other hand, knowing the magnetic configuration, one can analyse the polarization of a scattering beam [2]. Similar effects could also help to manipulate spin polarization of an electron current providing that the electrons interact with the known chiral magnetic structure.The ability to manipulate the electron spin is a necessary component for the spintronics [3], thus magnetic chiral organic molecules [4] or large scale magnetic structures have been proposed as such tools [5]. However, the question how to get the magnetic structure of a necessary chirality for spintronics applications is still open.Here we address the question for the case of Fe 1−x Co x Si solid solutions which, for certain compositions, show chiral (spiral) magnetic ordering [6][7][8].The structural chirality in monosilicides of 3d-metals is solely controlled by crystal growth [9]. A link between the structural and magnetic chiralities is provided by the Dzyaloshinskii-Moriya interaction (DMI) and has been experimentally proved for many monosilicides of 3dmetals [9][10][11][12].