Fe-W supermirrors for polarizing neutrons

Abstract

Polarized neutrons play an important role in scattering studies of condensed matter. Consequently, an efficient means of polarizing a neutron beam is very valuable. In addition to conventional, bulk single-crystal polarizers such as the Heusler alloy Cu{sub 2}MnAl, polarizing mirrors are often used for this purpose. Thin film bilayers of ferromagnetic Fe and nonmagnetic W have been deposited by sputtering on flat glass substreates according to a sequence of gradually varying bilayer thicknesses which in effect extends the critical angle for external mirror reflection for neutrons of one spin state when the Fe is magnetized in the plane of the film. The measured reflectivity of this Fe-W multilayer system is compared with that of other supermirror polarizers consisting of different materials and layer sequences. 14 refs., 3 figs