Crystal Chirality and Helicity of the Helical Spin Density Wave in MnSi. I. Convergent-Beam Electron Diffraction

The chirality of the intermetallic compound MnSi has been determined by the convergent-beam electron diffraction to reveal the specific relation between the chirality of the crystal and helicity of its helical spin density wave. It has been found that the crystals have the left-handed chirality. The left-handed crystal means that Mn and Si atoms occupy the positions reported by Borén (Arkiv. Kemi. Mine. Geol. 11A (1933) No. 10, 1) but the left-handed coordinate system should be adopted to describe the atomic positions in the unit cell.