Spin resolved bandstructure imaging with a high resolution momentum microscope

Abstract We present a spin resolving “momentum microscope” for the high resolution imaging of the momentum distribution of photoelectrons. Measurements of the band structure of a Au(111) single crystal surface demonstrate an energy resolution of Δ E = 12 meV and a momentum resolution of Δ k ∥ = 0.0049 A ˚ − 1 , measured at the line-width of the spin–orbit split Shockley surface state. The relative accuracy of the k ∥ measurement in the order of 10 − 4 A ˚ − 1 reveals a deviation from the ideal two-dimensional free electron gas model of the Shockley surface state, manifested in a threefold radial symmetry. Spin resolution in the full momentum image is obtained by an imaging spin-filter based on low-energy electron diffraction at a Au passivated Ir(100) single crystal. Using working points at 10.5 eV and 11.5 eV scattering energy with a completely reversed asymmetry of ±60% we demonstrate the efficient mapping of the spin texture of the Au(111) surface state.