Normal versus exchange inelastic electron scattering in metals: Theory and experiment

We compare the electron-energy-loss rate for bulk electronic excitations in a paramagnet with that in a ferromagnet. Both theory and experiment are presented, with the aim of clarifying the relative importance of normal versus exchange scattering in the two cases. Aluminum is chosen as our prototype paramagnet and Fe as the prototype ferromagnet. By studying the dimensionless ratio of normalized loss rates at low and high primary-electron energies, we obtain an interesting indicator for the relative importance of exchange processes.