Thermodynamically stable equal-module exchange magnetic classes
  It is shown that within the framework of application of the general scheme of the Landau theory of phase transitions to the magnetic crystals the equilibrium and stable equal-module exchange structures automatically appears in addition to the other magnetic states. No additional conditions such as the existence of the Andreev-Marchenko spin scalar are needed. Furthermore, they are not constrained by the dimensionality of irreducible representation as it typically takes place for the Andreev-Marchenko-type structures. 
Khisa Sh. Borlakov and Albert Kh. Borlakov (North Caucasian State   Humanitarian and Technological Academy)
cond-mat.str-el cond-mat.mtrl-sci cond-mat.other