Nanoscale control over single vortex motion in an unconventional superconductor

TL;DR

This study demonstrates nanoscale control over single vortex motion in an unconventional superconductor using a scanning tunneling microscope tip, advancing potential applications in vortex-based quantum computing.

Contribution

It introduces a method to create localized trapping potentials for vortices via tip-induced electronic modifications, enabling precise vortex manipulation in FeSe superconductors.

Findings

Nanoscale trapping potentials can be created with STM tips.

Vortex motion is suppressed along twin boundaries.

Tip-induced strain reduces superconducting gap locally.

Abstract

To realize braiding of vortex lines and understand the basic properties of the energy landscape for vortex motion, precise manipulation of superconducting vortices on the nanoscale is required. Here, we reveal that a localized trapping potential powerful enough to pull in the vortex line can be created with nanoscale precision on the surface of an FeSe superconductor using the tip of a scanning tunneling microscope. The mechanism of tip-induced force is traced to local modification of electronic properties and reduction of the superconducting gap, most likely due to tip-induced strain. Intriguingly, the tip-induced trapping potential is much less pronounced along the twin boundaries, dramatically reducing the vortice's degree of motion relative to the surrounding lattice. By enabling nanoscale manipulation of single vortices in Fe-based superconductors, and likely similar materials with strong strain-susceptibility of the superconducting gap, our findings provide an important step toward further development of vortex-based quantum information processing.