Solid and liquid vortex phases in superconducting Nb/V hybrids*

We have studied the vortex dynamics in a periodic potential created by local enhancement of superconductivity. This has been achieved by an array of Nb nanodots embedded in a V film of slightly lower critical temperature. A sample of Cu nanodots embedded in a V film is used as witness sample. In the former hybrid (Nb/V) the array of superconducting Nb dots induces: i) vanishing of commensurability effect between the vortex lattice and the Nb array; ii) hysteresis effects of the vortex dynamics in the solid phase; iii) softening of the vortex lattice, and iv) broadening of the liquid vortex phase. These outcomes can be controlled varying the temperature and/or the in-plane applied magnetic field.