Beamline I05 is a facility dedicated to the study of electronic structures by angle-resolved photoemission spectroscopy (ARPES). It provides an intense and highly monochromatic beam of vacuum ultraviolet radiation. Photoelectrons emitted from the sample are analysed by a high resolution angle-multiplexing electron analyser. A cryogenic sample manipulator is used to rotate the sample to cover different emission angles above the surface and thus different electron momenta. The spectrometer is housed in an ultrahigh vacuum to allow for optimum sample lifetime of the highly surface sensitive experiment. The resulting energy versus momentum maps are analysed to yield the band dispersions and Fermi surfaces and, owing to the high resolution, the spectral function of electrons near the Fermi level.
ARPES is applied to materials with exotic electronic ground states, such as unconventional superconductors (including high Tc materials), solids exhibiting charge and spin density waves, excitonic insulators and non Fermi liquids. Due to its intrinsically high surface sensitivity and accurate mapping of momentum parallel to the surface, VUV ARPES is particularly suitable for samples with layered structures and preferential cleavage planes.
The high-resolution branch
The high resolution branch (HR-ARPES) delivers a high flux of photons in a spot size of 50 x 50 (h x v) μm2. The energy resolution will allow efficient data taking at 5 – 10 meV energy resolution in the core operation range of 18 – 80 eV. Higher photon energies, up to 240 eV, can be used for band mapping. The end station will be equipped with a cryogenic six-degrees-of-freedom sample manipulator covering all emission angles in the temperature range 10 K < T < 300 K, and housed in an ultrahigh vacuum of 5x10-11 mbar. Sample load-lock, storage and a versatile preparation chamber are used for efficient sample change, in-situ preparation and characterisation.
The nano-ARPES branch features endstation that deliveres spatailly resolved ARPES from ultra-small spot with sizes approximately 0.7 x 0.7 µm2, obtained using Fresnel zone plate. Currently endstation operates in the energy range from 60 to 150 eV, providing ARPES experiment with combined resolution of 30-50 meV. The cryo-cooling system typically can cool sample down to 30K. Flexible adjustment of photoemission direction is possible with two-axes sample goniometer, rotation of analyser as well as deflection mode of analyser (Scienta DA-30). Sample load-lock, preparation and characterization chambers are available for user experiment as well.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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