Centro de Física da Universidade do Minho, 4710-057 Braga, Portugal.
J Phys Condens Matter. 2011 Nov 9;23(44):446003. doi: 10.1088/0953-8984/23/44/446003. Epub 2011 Oct 18.
The temperature versus magnetic field phase diagram of the 2D triangular lattice and multiferroic compound RbFe(MoO(4))(2) is analysed from the point of view of symmetry. The paramagnetic space group and its irreducible representations are used in order to obtain the magnetic symmetry of the possible modulated phases and characterize the restrictions imposed by this symmetry on the corresponding magnetic structures. Superspace symmetry is considered in the case of incommensurate phases. It is shown that the experimentally observed phases correspond to different isotropy subgroups originating in the same irreducible representation of the paramagnetic symmetry group. The relevant couplings between the primary transverse spin modulation and the electric polarization, the in-plane magnetization and the secondary longitudinal magnetic modulation are discussed. The mechanisms for the destabilization of the improper ferroelectric chiral phase and the origin of the different orientation of the spins with respect to the external field in the two collinear phases are analysed from a symmetry based perspective.
从对称的角度分析了二维三角晶格和多铁化合物 RbFe（MoO（4））（2）的温度与磁场相图。使用顺磁空间群及其不可约表示来获得可能的调制相的磁对称性，并表征该对称性对相应磁结构的限制。在非调幅相的情况下考虑超空间对称性。结果表明，实验观察到的相对应于源自顺磁对称群相同不可约表示的不同各向同性子群。讨论了初级横向自旋调制与电极化、面内磁化和次级纵向磁调制之间的相关耦合。从基于对称的角度分析了非理想铁电手性相失稳的机制以及两个共线相中相对于外场的自旋取向不同的起源。
