Vortex ratchet effect in single-crystal films of Bi2Sr2CaCu2O8+y

To explore the vortex ratchet effect in underlying spatially asymmetric potentials in high-Tc superconductors, we have measured vortex-flow and rectification resistance in Bi2Sr2CaCu2O8 + y (Bi2212) single-crystal films with an array of triangular holes fabricated using focused ion beam. The matching effect was observed in vortex-flow resistance in the sample with the array of triangular holes as well as that with the symmetric antidots arrays. In addition to that, we found a rectification effect in this sample. Multiple reversals of the rectification direction reflecting the net motion of vortices were observed as the magnetic field changes. In contrast to the vortex ratchet effects observed in conventional superconductors, the sign of the rectification sharply flipped in the matching fields.