We report a neutron diffraction study of the magnetic field- and impurity-induced ferroelectric states of the triangular lattice antiferromagnet CuFe1-xAlxO2. The magnetic structure of the ferroelectric phase was elucidated to be not a cycloidal structure, which can successfully lead to the electric polarization through the formula P ∝ eij x (Si x Sj) [H. Katsura et al.: Phys. Rev. Lett. 95 (2005) 057205], but a proper helical structure. Nevertheless, the fact that the helical magnetic ordering appears only in the ferroelectric phase among various magnetically ordered phases of CuFe1-xAlxO 2 strongly suggests that a spin noncollinearlity is relevant to the multiferroic nature in CuFe1-xAlxO2.
- Neutron diffraction
- Spin frustration
- Triangular lattice antiferromagnet
ASJC Scopus subject areas
- Physics and Astronomy(all)