Dynamic vortex Mott transition in triangular superconducting arrays

The proximity-coupled superconducting island arrays on a metallic film provide an ideal platform to study the phase transition of vortex states under mutual interactions between the vortex and potential landscape. We have developed a top-down microfabrication process for Nb island arrays on Au film by employing an Al hard mask. A current-induced dynamic vortex Mott transition has been observed under the perpendicular magnetic fields of f magnetic flux quantum per unit cell, which is characterized by a dip-to-peak reversal in differential resistance dV/dI vs. f curve with the increasing current. The dV/dI vs. I characteristics show a scaling behavior near the magnetic fields of f= 1/2 and f=1, with the critical exponents \varepsilon of 0.45 and 0.3, respectively, suggesting different universality classes at these two fields.