Novel type of spin cycloid in epitaxial bismuth ferrite films

We report on the novel cycloids that can be realized in epitaxial BiFeO3 films. We found two featured (1 1 0) and (11¯0) plane cycloids in the (1 1 0) oriented BiFeO3 film and considered the action of compressive and tensile deformations on the areas of the cycloids stability. Our findings show that additional magnetic anisotropy induced by the strains allocates cycloids with the definite directions of spin rotation and electric polarization and change the properties of space modulated structures. Until now, it was believed that polarization is linked with antiferromagnetic order throughout the plane of spin rotation, namely it was considered that polarization always lies in the cycloid spin rotation plane. We show that due to the action of epitaxial strains spin rotational plane of the cycloid deviates from the plane containing intrinsic spontaneous polarization Ps.