Quantum Size Effects on the Perpendicular Upper Critical Field in Ultrathin Lead Films

摘要

We report the thickness-dependent (in terms of atomic layers) oscillation behavior of the perpendicular upper critical field H_(c2⊥) in the ultrathin lead films at the reduced temperature (t = T/T_c). Distinct oscillations of the normal-state resistivity as a function of film thickness have also been observed. Compared with the T_c oscillation, the H_(c2⊥) shows a considerable large oscillation amplitude and a π phase shift. The oscillatory mean free path caused by the quantum size effect plays a role in H_(c2⊥) oscillation.