Symmetry analysis of modulated solid systems by line group method

Abstract

Line groups are proposed to describe the symmetry properties of systems with non-collinear magnetic structure. A general method is elaborated to obtain the irreducible representation of the symmetry groups of modulated crystals by using that of the line groups. As a demonstrative example, the stuctural phase transition leading to the modulated magnetic superstructure in MnAu₂ type compounds is analyzed by the employment of the line group technique. It is shown that the Dzyaloshinskii invariant is the most general one according to the symmetry properties investigated.