Element specific separation of bulk and interfacial magnetic hysteresis loops

Abstract

We have studied the reversal of the bulk and interfacial magnetizations of the free layer of a spin valve using soft x-ray resonant magnetic scattering. By dusting the interface of the NiFe free layer with a few angströms of Co, we were able to distinguish between the interfacial and bulk magnetisms by tuning the x-ray photon energy. We measured hysteresis loops of reflected x-ray intensity at selected points in reciprocal space. We find no difference in the switching fields, showing that in transition metal ferromagnets, the exchange interactions are sufficiently strong to prevent a separate interfacial coercivity from arising.

Room temperature magnetic stabilization of buried cobalt nanoclusters within a ferromagnetic matrix studied by soft x-ray magnetic circular dichroism

“…Such coupling has, for example, been observed previously in thin NiFe/Co films. 16 Noncollinear interfacial moments have also previously been observed in FM films; 17 this may introduce a small, e.g., biquadratic interfacial coupling term, resulting in canting of the net cluster moment from that of the NiFe film. However, we see no evidence of this from any of our measurements on these films.…”