Atomic-scale structure of electrically
induced dislocations and
stacking faults. (a) Bright-field TEM image and schematic of the cAFM
tip, illustrating that the perturbed crystal structure is restricted
to the area beneath the cAFM tip. (b) HAADF-STEM image viewed down
the [1̅00] direction, showing the as-grown state. (c) HAADF-STEM
image viewed down the [1̅00] direction, showing the region beneath
the position of the AFM tip after the application of the electric
field. The periodic crystal structure is interrupted by line features
extending in directions close to the ⟨011⟩ directions.
The bright and gray dots are Er and Mn atomic columns, respectively.
(d) Inverse fast Fourier transformation (FFT) obtained by selecting
only the (002) maxima of an FFT of panel b; see the insert. The image
shows areas with the same periodicity of the Er lattice, allowing
easier identification of lattice defects. Two edge dislocations are
highlighted by red and green circles. (e) Representative HAADF-STEM
image taken across the crystallographic features, corresponding to
the area marked by the red box in panel c. (f) Fully relaxed DFT supercell,
modeling the dislocated structure by unit cells dislocated by c/4 and a/3 with respect to each other.
Large gold and blue spheres represent Er atoms on either side of the
stacking fault; Mn and O atoms are sketched in purple and red, respectively.