ALBA II Colloquium #6 - "Soft X-ray XMCD at Ultra-Low Temperature"

Abstract

Ultra-Low Temperature (ULT: below 1 Kelvin) is of primary importance when dealing with new states of matter and the studies of magnetic phenomena. On the DEIMOS beamline at SOLEIL synchrotron a new ULT refrigerator dedicated to soft X-ray Magnetic Circular Dichroism (XMCD) allows now users to perform experiments down to 220mK. 

Preliminary experiments with an ErPd alloy and Fe4 molecules demonstrate the outstanding performances of this new set-up, in terms of lowest achievable temperature under x-rays, the precision in temperature control over 4 orders of magnitude, the speed of the cooling down/warming up procedures and the strongly reduced eddy current power, allowing fast scanning of the magnetic field during XMCD measurements.
In this presentation I will describe the modifications made to the 7Tesla cryo-magnet, used on DEIMOS beamline since 2010, in order to optimize its thermal shielding. I will also present the thermometric procedure we develop to calibrate the temperature at the sample place. 

About ALBA II Colloquium

The series ALBA II Colloquium, addressed to the scientific user's community of synchrotron radiation, is aimed at inspiring and promoting fruitful ideas and information exchange about the future development of ALBA II facility.