Differential phase contrast (DPC) STEM – From imaging magnetic domains to ferroelectric domain walls and oxygen vacancies.

Being able to map the electric and magnetic fields of a specimen within a scanning transmission electron microscope (STEM) offers new insights into the origin of physical properties, e.g. magnetism, of the investigated material. Differential phase contrast (DPC) is a method capable of providing these measurements by using the interaction of the imaging electrons with the electromagnetic fields [1,2]. Additionally, integrating atomic electric field structures enables to image light elements (and vacancies thereof) that otherwise are hard to detect. Here, we report how we used DPC measurements to investigate ferromagnetic domain structures of spinodal alloys, ferroelectric polarization domains of multiferroic doped bismuth ferrite (BFO), and how
integrated DPC (iDPC) can help identify oxygen vacancies of doped BFO. Moreover, high-angle annular dark field images (HAADF), energy-dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS) elemental maps were acquired and correlated to the DPC measurements. Thereby, new insights into the relationship between compositional and magnetic and electric properties are gained.