Spin-polarized electron energy-loss spectroscopy and the stoner excitation spectrum of iron

Abstract

Stoner excitations are elementary excitations of ferromagnets, characterized by an electron-hole pair of opposite spin and well-defined momentum. This excitation mode can be probed via exchange processes in inelastic electron backscattering from ferromagnetic surface. For a detailed study of direct and exchange processes a “complete” scattering experiment is carried out: Spin-polarized primary electrons from GaAsP are accelerated onto a remanently magnetized Fe surface. The scattered electrons are selected with respect to scattering angle and energy loss, and subsequently analyzed with respect to spin. The generation of a Stoner pair is indicated by the detection of an electron with spin opposite to that of the primary electron. By measuring the energy loss and the scattering angle the spectrum of Stoner excitations in energy-momentum space is experimentally evaluated. Experimental results for Fe(100) and Fe(110) are compared to a calculated Stoner density of states.