Scanning Electron Microscopy with Polarization Analysis (SEMPA) is a technique for the high spatial resolution imaging of magnetic microstructure. It employs a Scanning Electron Microscope (SEM) to create a finely focused electron beam on the surface of a ferromagnet; secondary electrons excited by the incident beam retain their spin-polarization when exiting the surface. A two dimensional map of the electron spinpolarization of these secondary electrons reveals the surface magnetization distribution for ferromagnetic (or ferrimagnetic) systems. This chapter describes salient features of the electron probe forming optics, the electron spin-polarization analyzers with associated transport optics, and the signal processing electronics. We also give examples illustrating how SEMPA provides high resolution magnetization images of various classes of micromagnetic structure.

Polarized neutron reflectivity and scanning electron microscopy with polarization analysis are combined to determine the magnetic structure of Co(6 nm)͞Cu(6 nm) multilayers. These data resolve a controversy regarding the low-field state of giant-magnetoresistive (GMR) multilayers with weak coupling. As-prepared samples show a strong antiparallel correlation of in-plane ferromagnetic Co domains across the Cu. At the coercive field, the Co domains are uncorrelated. This irreversible transition explains the decrease in magnetoresistance from the as-prepared to the coercive state. For both states, the Co moments reside in domains with in-plane sizes of ഠ0.5 1.5 mm.[S0031-9007(99)08797-9]

No abstract

No abstract

We have imaged the magnetic domain structure of several heterogeneous Co x Ag 1Ϫx alloys by using scanning electron microscopy with polarization analysis. These images show that extended domain structures exist in both the as-deposited samples and in samples annealed at moderate temperatures. This suggests that a significant fraction of the cobalt in these materials does not contribute to the giant magnetoresistance. Only those samples annealed at 600°C and containing less than 40% cobalt by volume show no domain structure.