Title: Nanoscale assembly of superconducting vortices with scanning tunnelling microscope tip,
Abstract: Vortices play a crucial role in determining the properties of superconductors
as well as their applications. Therefore, characterization and manipulation of
vortices, especially at the single vortex level, is of great importance. Among
many techniques to study single vortices, scanning tunneling microscopy (STM)
stands out as a powerful tool, due to its ability to detect the local
electronic states and high spatial resolution. However, local control of
superconductivity as well as the manipulation of individual vortices with the
STM tip is still lacking. Here we report a new function of the STM, namely to
control the local pinning in a superconductor through the heating effect. Such
effect allows us to quench the superconducting state at nanoscale, and leads to
the growth of vortex-clusters whose size can be controlled by the bias voltage.
We also demonstrate the use of an STM tip to assemble single quantum vortices
into desired nanoscale configurations.