Al/Nb bilayer superconducting density of states measurements at 4 K

Tunneling spectroscopy is performed using tunnel junctions with a thin film Al/Nb hybrid superconducting bilayer. With this hybrid Al/Nb system, we take advantage of the relatively high superconducting critical temperature of Nb (9.2 K in bulk) and the low spin-orbit coupling of Al (b ) for Meservey-Tedrow type measurements near liquid helium temperatures (4 K). While altering the thickness of the bilayer elements, we measure the bilayer superconducting transition temperature and tunneling spectroscopy density of states to explore the interplay of the superconducting proximity effect and spin orbit coupling between the Al and Nb.