Amorphous and Crystalline Magnetic/Superconducting Hybrids: Interplay Between Periodic Defects and Random Defects

Arrays of nanometric Ni dots embedded in amorphous
${\rm Mo}_{3}{\rm Si}$

$(a-{\rm Mo}_{3}{\rm Si})$
or crystalline Nb superconducting films modify the vortex lattice dynamics and the dissipation mechanisms, close to critical temperatures. The vortex lattice force vs. velocity characteristics have been measured in both hybrids. The velocities of the ordered and synchronized vortices are the same in both systems (hybrids based on Nb films or
$a-{\rm Mo}_{3}{\rm Si}$
films), but remarkably the needed driving forces are one order of magnitude smaller in
$a-{\rm Mo}_{3}{\rm Si}$
hybrids than in Nb based hybrids. This experimental behavior points out magnetic/superconducting hybrids, based on amorphous superconductors films, could be a promising material for controlling vortex motion with very low driving forces.