  Dislocations are one-dimensional (1D) topological line defects where the
lattice deviates from the perfect crystal structure. The presence of
dislocations transcends condensed matter research and gives rise to a diverse
range of emergent phenomena [1-6], ranging from geological effects [7] to light
emission from diodes [8]. Despite their ubiquity, to date, the controlled
formation of dislocations is usually achieved via strain fields, applied either
during growth [9,10] or retrospectively via deformation, e.g., (nano
[11-14])-indentation [15]. Here we show how partial dislocations can be induced
using local electric fields, altering the structure and electronic response of
the material where the field is applied. By combining high-resolution imaging
techniques and density functional theory calculations, we directly image these
dislocations in the ferroelectric hexagonal manganite Er(Ti,Mn)O3 and study
their impact on the local electric transport behaviour. The use of an electric
field to induce partial dislocations is a conceptually new approach to the
burgeoning field of emergent defect-driven phenomena and enables local property
control without the need of external macroscopic strain fields. This control is
an important step towards integrating and functionalising dislocations in
practical devices for future oxide electronics.
