k-Space tomography of the Fermi surface by spatially resolved photoemission spectroscopy with variable photon energy

Abstract When mapping spatially resolved photoemission intensity for electron kinetic energy corresponding to Fermi energy, one obtains a spherical cut through a three-dimensional Fermi surface of a metal. At the APE-INFM beamline at Elettra, we developed an automated method of measuring the Fermi surface cuts for a large number of photon energies and putting them together in order to reconstruct the three-dimensional Fermi surface. The energy and k ∥ (momentum parallel to the surface) resolution are set by the monochromator and energy analyzer properties, while the k ⊥ (momentum perpendicular to the surface) resolution depends on the photon energy step chosen for obtaining subsequent data sets. By 3D interpolation of the data, one obtains the k -space tomography of the constant initial state surfaces (e.g. of the Fermi surface). From the tomography, one can retrieve true k x , k y , k z resolved maps. Besides de Haas van Alphen (dHvA) oscillations, this method is the most direct way for the determination of the Fermi surfaces. A set of data on the Fermi surface of Be(0 0 0 1) is presented and compared to dHvA data and theory.