Superconducting properties of V/Fe superlattices

We report measurements on the superconducting properties of V/Fe superlattices with various layer thicknesses. These samples were prepared with a novel UHV evaporator which can produce up to twenty different samples in the same run. The Fe layer, a strong pair breaker, suppresses the superconducting transition temperature in a systematic way. When the V layer thickness is on the order of the BCS coherence length and the Fe layer is only a few atomic planes thick, a 2D–3D crossover has been observed in the temperature dependence of the parallel upper critical field H_C2∥. This implies the coexistence of superconductivity and ferromagnetismm. We observe three dimensional behavior for thinner Fe layers (～1 atomic plane) and two dimensional behavior for thicker Fe layers (greater than 10 atomic planes).