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

Abstract

We present a quantitative comparison of the magnetization measured by spin-polarized neutron reflectivity ͑SPNR͒ and dc magnetometry on a 1370 Å-thick Nb superconducting film. As a function of magnetic field applied in the film plane, SPNR exhibits reversible behavior whereas the dc magnetization shows substantial hysteresis. The difference between these measurements is attributed to a rotation of the vortex magnetic field out of the film plane as the applied field is reduced. SPNR measures only the magnetization parallel to the film plane, whereas dc magnetization is strongly influenced by the perpendicular component of magnetization when there is a slight sample tilt; thus combining the two techniques allows one to distinguish two components of magnetization in a thin film.

Distribution of vortices in Nb/Al multilayers studied by spin-polarized neutron reflectivity and magnetization

“…After cycling the field to 5400 Oe, SPNR measurement was also conducted from the multilayer at 2000 Oe, as shown in Fig. with a theoretical model [15]. The M shows that is unable to distinguish the differences among the fields due to large uncertainty.…”

“…A theoretical model calculation by Han et al [13] has demonstrated that it could be able to measure the density and also the distribution of vortices. By using another advantage of SPNR that measures only parallel component of magnetization due to a scattering selection rule, Han et al [15] has demonstrated that vortices placed perpendicular to surface considerably contribute to the magnetization measurements even at a small tilted field.…”

Neutron scattering studies of nanomagnetism and artificially structured materials

“…For example, small-angle neutron scattering has been used to map out the vortex lattice phase diagram as a function of magnetic field and temperature [165,166,167,168,169] for arrays of vortices forming an hexagonal or a square lattice at the surface [170]. For thin films, the vortex distribution parallel to the film has been determined from polarized neutron reflectometry [171,172,173,174].…”

Magnetic Imaging of Pearl Vortices in Artificially Layered(Ba0.9Nd0.1CuO2+x)

“…(1) to find hx; y; z, integrating the result over the known pickup loop geometry, and using as the fitting parameter. The height z was determined by fitting images of vortices in Nb with the same SQUID magnetometer, assuming an isotropic low temperature Nb penetration depth of 0:05 m [17]. We note that although the peak SQUID flux s depends strongly on , the fullwidth at half-maximum of the vortex images is relatively independent of for such thin films.…”