Abstract
A new ultralow-temperature setup dedicated to soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) experiments is described. Two experiments, performed on the DEIMOS beamline (SOLEIL synchrotron), demonstrate the outstanding performance of this new platform in terms of the lowest achievable temperature under X-ray irradiation (T = 220 mK), the precision in controlling the temperature during measurements as well as the speed of the cooling-down and warming-up procedures. Moreover, owing to the new design of the setup, the eddy-current power is strongly reduced, allowing fast scanning of the magnetic field in XMCD experiments; these performances lead to a powerful device for X-ray spectroscopies on synchrotron-radiation beamlines facilities.
Highlights
The synchrotron-based X-ray absorption spectroscopies, X-ray magnetic circular dichroism (XMCD) and linear dichroism (XLD), are useful techniques in physics, chemistry and materials science because of their chemical selectivity and high sensitivity
A new ultralow-temperature setup dedicated to soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) experiments is described
Owing to the new design of the setup, the eddy-current power is strongly reduced, allowing fast scanning of the magnetic field in XMCD experiments; these performances lead to a powerful device for X-ray spectroscopies on synchrotron-radiation beamlines facilities
Summary
The synchrotron-based X-ray absorption spectroscopies, X-ray magnetic circular dichroism (XMCD) and linear dichroism (XLD), are useful techniques in physics, chemistry and materials science because of their chemical selectivity and high sensitivity They allow investigation of diluted elements in the first nanometres of bulk samples down to a concentration of few hundred p.p.m., and collections of single molecules or atoms on surfaces (Van der Laan & Figueroa, 2014; Stohr et al, 1998). The installation of this system in the DEIMOS beamline allows the possibility of in situ sample transfer to/from additional UHV chambers and a glove box, providing possibilities for specific in situ sample preparation (ion sputtering, temperature annealing up to 1000C, metal and organic layer deposition) and characterization (scanning tunneling microscopy, electron diffraction, Auger spectroscopy) For these in situ prepared samples, special holders have been developed that allow us to reach sample temperatures very close to Tlim. We illustrate the XMCD at the Er-M4,5 edges in the paramagnetic Er0.025Pd0.975 alloy; by recording the Fe-L2,3 edges, we probe the metastable behavior of a Fe4 single-molecule magnet (SMM) chemisorbed as a monolayer on Au(111)
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