Reentrant Superconductivity in Aluminum Thin Films under High Magnetic Field

A reentrant superconducting transition was observed for the first time around the magnetic field, 3 T and the temperature, 0.5 K for Al thin films parallel to the magnetic field. The reentrant second order transition is discussed on the basis of Fulde's theory with regard to the spin paramagnetic effect which is competitive with the orbital depairing effect under high magnetic field.