Scanning Electron Microscopy with Polarized Electrons
John Unguris, G Hembree, Robert Celotta, Daniel T. Pierce
The recent joining of scanning electron microscopy and electron spin polarization analysis has greatly improved the ability to study magnetic microstructure. By measuring the spin polarization of secondary electrons, scanning electron microscopy with polarization analysis (SEMPA) can directly measure the magnitude and direction of the magnetization and direction of the magnetization in the region probed by the incident electron beam. This region is defined by the diameter of the incident electron beam (10 nm) and the escape depth of the secondaries (5 nm). In addition to the purely magnetic image SEMPA also simultaneously and independently measures the usual topographic image, thereby making comparisons between magnetic and topographic structures easier. We have successfully used SEMPA to study magnetic structures in Fe crystals, permalloy films, CoNi recording media, and metglasses. Examples from this work will be given in order to demonstrate the unique capabilities of SEMPA.