Interplay between crystalline chirality and magnetic structure in ${\text{Mn}}_{1-x}{\text{Fe}}_x\text{Si}$

X-ray diffraction using synchrotron radiation and polarized neutron small-angle diffraction have been used to evaluate the absolute crystallographic structure and the spin helix chirality of ${\text{Mn}}_{1-x}{\text{Fe}}_x\text{Si}$. Contrary to previous observations we show that left- and right-handed crystals can be found for MnSi and its iron substituted analogs. The structural chirality rigorously determines the magnetic chirality of these compounds: left-(right-)handed crystalline chirality establishes left (right) handedness of the magnetic helix.

Figure 1

(Color online) View of the crystal structure of MnSi [$P{2}_{1}3$ structure with the atomic coordinates $\left(u,u,u\right),\left(1/2+u,1/2-u,-u\right),\left(1/2-u,-u,1/2+u\right),\left(-u,1/2+u,1/2-u\right)$] along the (111) axis for $u_{\text{Me}}=0.137$ and $u_{\text{Si}}=0.845$ (a) and for $u_{\text{Me}}=0.863$ and $u_{\text{Si}}=0.155$. (b) The chirality of the Si sublattice is left handed for the atomic configuration in (a) and right handed for the atomic configuration in (b).