Imaging ferroelectric domains with soft X-ray ptychography at the oxygen K-edge

The ferroelectric domain structure of a freestanding BiFeO₃ film was visualized by ptychographic dichroic imaging with linearly polarized X-rays at the O K-edge around 530 eV. The dichroic contrast is maximized at the energy of the hybridization of the O 2p state and the Fe 3d orbitals, which is split by the octahedral crystal field of the perovskite structure. The thus obtained microscopy images compliment the ptychographic imaging of the antiferromagnetic contribution at the Fe L₃-edge. The approach is extendible to the separation of different ferroic contributions in other multiferroic oxides.