The plasmons of ErAs(100)

Momentum resolved inelastic electron energy loss has been exploited to measure the surface and bulk plasmons of ErAs(100). The effects of the electronic band structure are seen in the weak plasmon dispersion, and a contribution to the surface and bulk plasmons, from the Er 5d bands, is indicated in the decrease in the surface plasmon frequency by about 10% from the free electron value and to a ratio of the bulk and surface plasmon energies of about √3