DECOUPLING OF SUPERCONDUCTING-V BY ULTRATHIN FE LAYERS IN V/FE MULTILAYERS

We report on a detailed study of superconducting critical temperatures T(c) and critical fields H(c2) Of V/Fe multilayers. The thickness of the V layers (d(V)) and Fe layers (d(Fe)) as well as the total number of layers ip the multilayer (N) were varied systematically. For d(Fe) greater-than-or-equal-to 0.6 nm, at constant d(V), T(c) and the critical fields for parallel (H(c2 parallel-to)) and perpendicular (H(c2 perpendicular-to)) orientation do not depend on either d(Fe) or N, and a two-dimensional (2D) temperature dependence for H(c2 parallel-to) without 3D-2D crossover is observed for small values of d(V). The predicted oscillatory behavior of T(c) as a function of d(Fe) is not found. We conclude that the superconducting V layers are completely decoupled by only 0.6 nm Fe, in conflict with previous reports. Upon decreasing d(V) at constant d(Fe), a strong decrease of T(c) is found. This, together with the temperature dependence of H(c2 parallel-to) and H(c2 perpendicular-to) for all samples can be described by existing theory.