Determination of Tc, vortex creation and vortex imaging of a superconducting Nb film using low-temperature magnetic force microscopy

Using a custom built low temperature magnetic force microscope, we have used the repulsive Meissner interaction between the magnetic tip and the sample to determine the critical temperature of a superconducting Nb film. Vortex creation by the tip stray field has been observed, in which two vortices have been nucleated, both simultaneously and in succession. We have also imaged vortices as a function of applied magnetic field, and have observed the expected linear dependence between vortex density and field strength