Spin-resolved Photoemission Spectroscopy (SARPES)

Photoemission spectroscopy has become the key technology for the investigation of electronic properties of promising materials such as Heusler compounds, Weyl systems, materials with Rashba effect, topological insulators or metal-organic interfaces. In recent years, the efficiency of photoemission spectroscopy has been greatly enhanced by introducing parallel imaging. However, the analysis of the spin polarization remained time-consuming. Since potentially suitable materials for spintronic applications such as metal-organic interfaces tend to deteriorate rapidly, a significant reduction in the duration of spin-resolved data is necessary.

A newly developed and powerful imaging spin filter, based on a large Ir (001) scattering crystal, addresses this problem by increasing the measuring efficiency. An increase of the effective figure of merit by a factor of more than 10³ in contrast to conventional single-channel detectors is achieved. In particular, the spectrometer resolution is determined in the energy and impulse space. The energy and angle resolution is 27 meV or 0.23 ° for an energy and angular acceptance of 1.5 eV or +/- 10 °. The spin filter efficiency is mapped and analyzed over large energy and angular ranges. Under ideal conditions, a Sherman function of up to 0.44 is measured. If the scattering plane coincides with a mirroring plane of the crystal, the spin filter is only sensitive to the component of the spin vector perpendicular to the scatter plane. Plots which do not coincide with a mirroring plane result in a high sensitivity for components of the spin vector parallel to the scattering plane. A spin rotator element allows the independent determination of the two in-plane components of the spin vector. By combining three or six scattering conditions, a vectorial spin analysis becomes possible for magnetic and non-magnetic samples.