Orientation of vortices in a superconducting thin film: Quantitative comparison of spin-polarized neutron reflectivity and magnetization

We present a quantitative comparison of the magnetization measured by spin- polarized neutron reflectivity (SPNR) and dc magnetometry on a 1370 Angstro m-thick Nb superconducting film. As a function of magnetic field applied in the him plane, SPNR exhibits reversible behavior whereas the de magnetizat ion shows substantial hysteresis. The difference between these measurements is attributed to a rotation of the vortex magnetic field out of the film p lane as the applied field is reduced. SPNR measures only the magnetization parallel to the him plane, whereas de magnetization is strongly influenced by the perpendicular component of magnetization when thew is a slight sampl e tilt; thus combining the two techniques allows one to distinguish two com ponents of magnetization in a thin film.