6533b85bfe1ef96bd12bb3f1

RESEARCH PRODUCT

Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100)

subject

description

We demonstrate a finite spin polarization of photoelectrons emitted from GaAs(100) covered by a fractional Ag film. The photoemission yield shows a sharp maximum for intermediate coverage and the spin polarization increases with increasing laser intensity. Photoelectrons are excited by circularly polarized 100 fs laser pulses of 800 nm wavelength. We recorded the photoemitted electrons using a photoemission electron microscope combined with a Mott spin polarimeter. The spin polarization is analyzed in dependence on the excitation frequency and intensity and on the average thickness of the silver film. The results are explained by a model combining multiphoton photoemission and optical field emission. Our observation suggests a coherent excitation of circularly polarized plasmons and a transfer of angular momentum to the spin of photoemitted electrons.