Fig. 6: Ptychographic images.
a Amplitude and b Phase ptychographic images of a Siemens star. These images were obtained with an exposure time of 2.5 ms. c X-ray linear dichroism image (phase contrast) showing the in-plane projection of the ferroelectric polarisation (P). Mosaic-like multiferroic domains are visible, which contain spin cycloids (64 nm period) in an 80 nm thin freestanding BiFeO3 (001) film. The crystallographic axes of the BiFeO3 film are indicated above the color bar. The contrast indicates both the in-plane axis of P in the BiFeO3 film and delineates the spin cycloid coupled within the multiferroic domains (see refs. 63,64 for details). All images were acquired with an X-ray energy of ~707 eV (Fe L3-edge). At this energy, the maximum of the XLD contrast originating from the BFO ferroelectric domains is found in the phase information.
