Spin polarization of ion-excited secondary electrons from ferromagnets and its application for magnetic sputter depth profiling

We study the spin polarization of secondary electrons from Fe(110) excited by noble-gas ions from 0.5 to 4 keV energy, covering the range potential emission to kinetic emission of secondary electrons. We find majority-spin polarization at all energies and for all ion species, but less than with primary electrons from the same sample. There is no magnetically ``dead'' layer produced, even by heavy sputtering. This leads to the possibility of ``magnetic sputter depth profiling'' which is demonstrated by sputter profiling through a 50-A{} iron oxide layer on iron while the secondary-electron spin polarization is monitored.