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S C I E N T I F I C H I G H L I G H T S
E L E C T R O N I C S T R U C T U R E , M A G N E T I S M A N D D Y N A M I C S
The beamlines ID12, ID20, ID26, ID28 and ID32 in the Electronic Structure, Magnetism & Dynamics (EMD) group were operational in 2021 and the staff made enormous efforts to keep the experimental stations as productive as possible under the difficult circumstances of the COVID-19 pandemic. The sample environment unit was in great demand as many user groups sent equipment that had to be operated by the ESRF staff on the experimental stations.
The main emphasis for ID12 was to exploit the X-ray Magnetic Circular Dichroism (XMCD) end-stations, which offer unique possibilities for fundamental research in magnetism. One is based on a fast-sweeping, 8T superconducting solenoid. It is dedicated to XMCD experiments under external stimuli, such as visible light excitation, electric field or high pressure. The latter greatly benefits from the new EBS source, which provides a beam of circularly polarised X-rays 10 times more intense than previously, with a spot size of less than 5 microns. Recently, this end-station was equipped with a new insert that allows users to perform XMCD experiments at temperatures up to 1000 K. This versatile instrument is complementary to the high-field XMCD end-station based on a 17T solenoid that is one of the most frequently requested instruments at the ESRF. Two articles nicely illustrate the possibilities on ID12. One study by Perlepe et al. (page 106) unravels the microscopic origin of magnetism in newly discovered metal-organic magnets with high coercivity and unprecedented ordering temperature up to 515 K. Sokolov et al. (page 115) investigated 2D magnetic states in a graphene-based monolayer of EuC6.
During the first half of 2021, the staff on beamline ID20 assembled, installed and commissioned an energy- dispersive spectrometer in von-Hamos geometry. The instrument is now available to all users of ID20. This new spectrometer was used during several experiments in the second half of 2021 to measure non-resonant valence- to-core X-ray emission lines of several 3d transition metal elements, while acquiring core electron excitation spectra of oxygen and silicon via X-ray Raman scattering (XRS) spectroscopy. As scientific highlights from ID20, we present a study by Moya-Cancino et al., who deciphered the formation of cobalt-carbide in a Co/TiO2 catalyst during a Fischer-Tropsch Synthesis (FTS) reaction using a combination of XRS spectroscopy and X-ray diffraction (page 107). Ye et al. utilised the high-energy-resolution spectrometer at ID20 to measure X-ray absorption spectra