Comunicazione
Vortex lattice instability in superconducting materials.
Grimaldi G., Leo A., Khan M.R., Martucciello N., Nigro A.
Depending on material defects, vortex physics reveals a variety of phenomena that make up a complex magnetic field-temperature phase diagram for superconductors. By driving at high velocities the vortex lattice under current bias its stability can become challenging and in recent years an overall study has been carried out on how to tune this instability by acting on material properties and geometry. In low- high-temperature as well as in Fe-based superconductors, this instability occurs with different features related to the material itself. Nevertheless, a common phenomenological scenario of critical vortex velocities as a function of temperature and magnetic field can be empirically depicted by measurements. Additionally, the size effects have been systematically studied by playing either with a mesoscopic scale or with a nanoscale geometry of samples. We finally draw a reference picture in which by changing width or thickness of sample, temperature and material pinning, anisotropy and angular field orientation as well, it allows for a predictable behaviour of the critical vortex velocity. Our findings unveil unexpected experimental trends within current theoretical frameworks.