  To date, high-resolution electron microscopy has largely relied on using the
phase of the exit wave function at the exit surface to form a high-resolution
electron microscopic image. We have for the first time used chromatic
aberration correction to implement a new imaging mode to achieve amplitude
contrast imaging in high-resolution electron microscopy, allowing us to obtain
directly interpretable high-resolution electron microscopic images with
discrimination between light and heavy atomic columns. Using this imaging
approach, we have successfully visualized the atomic structure in a
BaTiO3/CaTiO3 superlattice with high spatial accuracy and discrimination
between Ba and Ca columns, providing direct visualization of the Ca and Ba
associated oxygen octahedral tilt that controls ferroelectric behavior in these
superlattice structures. Furthermore, this approach offers new opportunities to
unravel the structure in a wide range of materials, especially complex oxides
with exotic behaviors based on specific structural arrangements.
