Magnetic profile in Nb Si superconducting multilayers

Polarized neutron reflectivity measurements were conducted on [Nb(100 Angst rom),Si(15 Angstrom)] x N superconducting multilayers with a Tc similar to 7.5 K. Scope of the experiment was to verify the existence of arrays of vor tices parallel to the surface above the critical field H-c1 = 400 Oe when a magnetic held was applied parallel to the film plane. Measurements at 1.6 K and 700 Oe in the zero-held-cooled condition, and at 30 Or after field co oling, indicated that reflectivity close to the first Bragg reflection of t he multilayer was significantly dependent on the neutron spin. This effect was interpreted as due to Josephson-type vortices at and around the silicon layers. (C) 1999 Elsevier Science B.V. All rights reserved.