  Superconductors often contain quantized microscopic whirlpools of electrons,
called vortices, that can be modeled as one-dimensional elastic objects.
Vortices are a diverse playground for condensed matter because of the interplay
between thermal fluctuations, vortex-vortex interactions, and the interaction
of the vortex core with the three-dimensional disorder landscape. While vortex
matter has been studied extensively, the static and dynamic properties of an
individual vortex have not. Here we employ magnetic force microscopy (MFM) to
image and manipulate individual vortices in detwinned, single crystal
YBa2Cu3O6.991 (YBCO), directly measuring the interaction of a moving vortex
with the local disorder potential. We find an unexpected and dramatic
enhancement of the response of a vortex to pulling when we wiggle it
transversely. In addition, we find enhanced vortex pinning anisotropy that
suggests clustering of oxygen vacancies in our sample and demonstrates the
power of MFM to probe vortex structure and microscopic defects that cause
pinning.
