Scientists at Japan's Research Center for Materials Nanoarchitectonics (MANA), part of NIMS, studied an ultrathin superconductor whose surface had regularly spaced atomic steps. Using scanning tunneling microscopy, they directly observed quantum vortices—tiny magnetic structures that can disrupt superconducting performance—positioned along these steps.
Four-terminal resistance measurements revealed a striking directional difference: vortices moved more than 1,000 times more easily along the steps than across them. The team, led by Takashi Uchihashi, also found that this guiding effect could be adjusted simply by changing temperature or magnetic field. In a field range of roughly 0.10 to 0.20 tesla, vortices flowed freely along the steps without being trapped by material imperfections.
At the lowest temperatures, vortex motion was governed by quantum tunneling, allowing vortices to pass through barriers that classical physics would forbid. The results, published in Physical Review B, suggest that atomic-scale surface features could serve as natural tracks for controlling quantum motion. While practical applications remain distant, this approach may eventually help engineers manage vortex movement and heat flow in future superconducting electronics that consume far less power.