Making superconductors thinner can change how they accommodate magnetic fields

What happens when a superconductor becomes so thin that electrons can no longer behave as if they were moving through an ordinary three-dimensional piece of metal? This question has been at the center of my recent work on quantum confinement in metallic films. Over the past few years, I have been developing this line of theory with my colleague Giovanni Ummarino at Politecnico di Torino. Our initial goal was to understand something rather concrete: Why does shrinking the thickness of a superconducting film change the temperature at which superconductivity appears?