Two-dimensional high-order commensurate structure in DyRu2Si2

DyRu2Si2 has a commensurate structure with a wave vector Q=(((2)/(9)),0,0) below TN=29 K, and undergoes a phase transition to a two-dimensional high-order commensurate structure at 3.5 K. The phase transition was studied with a molecular field model involving wave vector-dependent molecular field coefficients. The results of calculations of the moments, wave-like molecular fields and free energies were presented. The appearance of the two-dimensional structure is discussed in connection with the molecular field coefficients