High pressure XANES and XMCD in the tender X-ray energy range

ABSTRACT

We have developed an experimental setup at the ESRF beamline ID12 dedicated to X-ray absorption and magnetic circular dichroism measurements at high pressure adapted for the tender X-ray energy range and compatible with low temperatures and with high magnetic field. The focused incoming X-ray beam passes through a thin diamond disk attached to a fully perforated diamond anvil and X-ray fluorescence photons from the sample are collected in back-scattering geometry through the same diamond disk. The pressure in the cell is measured using the ruby luminescence through a full diamond anvil. The highest pressure attainable with this diamond anvil cell (DAC) depends on the thickness of the diamond disk and it is above 16 GPa for a 80-μm thick plate and exceeds 4.5 GPa in the case of 30-μm diamond disk. Excellent performances of this setup in the tender X-ray range are illustrated with X-ray absorption near-edge structure studies of the phase transitions in KCl at the potassium and chlorine K-edges (3.61 and 2.82 keV, respectively) as well as in CdS at the sulfur K-edge (2.47 keV). This DAC together with a dedicated total fluorescence yield (TFY) detector could be mounted in the main heat exchanger of a cryostat and inserted in a bore of a superconducting magnet, this makes possible to perform X-ray magnetic circular dichroism (XMCD) experiments at low temperature, high magnetic field and high pressure. Feasibility of this approach is shown with the XMCD results obtained at the U M${}_{4,5}$-edges in ferromagnetic superconductor UGe${}_2$.

KEYWORDS:

• X-ray absorption
• X-ray magnetic circular dichroism
• tender X-rays

Acknowledgments

F. W. would like to acknowledge M. Mezouar for the strong support during the feasibility study of this project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

A. S. thanks for financial support the Ministry of Science and Education of Russian Federation [grant number N° 14.Y26.31.0002]. This work was performed at the beamline ID12 of the European Synchrotron Radiation Facility (ESRF) and is supported by the ESRF.