XMCD end-station

A custom built high-field superconducting magnet integrated with an in-situ sample preparation system. This end-station is designed for x-ray magnetic circular and linear dichroism experiments (XMCD/XMLD).

High-Field Magnet

This custom built magnet was designed especially for Soft X-ray XMCD and XMLD measurements. The magnetic field of 9 Tesla along the beam direction can be ramped at 8 Tesla per minute, and a magnetic field of 4 Tesla perpendicular to the beam direction can be ramped at 2 Tesla per minute. However, we typically ramp at 3T/min along the beam and 1T/min perpendicular to the beam, though we can adjust the rate depending on the required fields and the experimental need.

The sample is vacuum-mounted onto a LHe variable temperature insert that can reach ~6 K, but should be improved in the near future to ~3K, and can go up to 325K. This insert can be rotated over 360 degrees about the vertical axis. The sample space is ultra-high vacuum (10^-10 to 10^-11 mbar base pressure with sample at room temperature), obtained by cryo-pumping of the liquid helium can. Absorption spectra can be simultaneously measured in drain current and total fluorescence yield mode, and if requested in transmission.

Sample Preparation

The magnet is connected in ultra-high vacuum to a cluster of chambers for in-situ sample preparation and characterisation. The capabilities of the system can be extended by users who wish to bring their own chambers to prepare samples for their experiment in situ.

Ex-Situ Samples	Thin Films	Molecules & Low Vapour Pressure Materials
Load-lock Sputtering Annealing to 500°C Sample Cleaver & Scraper Up to 2 Evaporation Sources Storage of 5 Samples UHV Ports for User Tools	Up to 4 Evaporation Sources Wedge Growth Quartz Microbalance Monitor Sputtering Cooling & Annealing (< 100 - 2300 K) Gas Dosing Auger Electron Spectroscopy (AES) LEED	Up to 4 Evaporation Sources Wedge Growth Quartz Microbalance Monitor Sputtering Cooling & Annealing (< 100 - 1500K) Gas Dosing LEED & µA LEED
Omicron VT-STM	User Port	Sample Storage
70 - 300 K STM Tip Preparation Tool In-situ Evaporation	Load-lock (standard) Ar glove-box UHV suitcase User Set-ups	Up to 20 Samples

XES spectrometer

A compact, high through-put XES/RIXS spectrometer is currently being built. It is expected to go into user operation for the scheduling period 2023/II (Aug 2023 to Feb 2024). The spectrometer can be connected to the HFM end station in 90° horizontal scattering geometry. It will enable RIXS-MCD measurements in magnetic fields up to 9 Tesla and temperatures down to 4K.

More information on the spectrometer can be found on the poster linked below.

Sample Holders

We have developed a range of sample holders in high-purity aluminum or copper. Samples can be glued or clamped down.

A special sample holder using Omicron plates for single crystals is available. Sample size can be anything between 2 mm and 14 mm.

The screws are molybdenum, and Omicron plates used are mostly tantalum, with tungsten or molybdenum plates also available. This is because they must be non-magnetic for use in the HFM

Sample Holder Type 1: Plate Screwed into Shuttle

Sample Holder Type 2: Omicron Plate Slid into Shuttle

The Omicron plate dimensions are contained within this document - the plate is covered by 1mm at each end when slotted in the holders, thus the effective width of the plate is 16mm (2mm reduced).

Sample size

Samples should have a minimum size of 0.7 × 0.05 mm² (horizontal × vertical). For smaller sizes contact us in advance. Since the beam spot dimensions are adjustable, spot sizes of up to several millimeters are also possible.

For more information please contact the beamline staff and/or see the following publication.

The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32
K. Kummer, A. Fondacaro, E. Jimenez, E. Velez-Fort, A. Amorese, M. Aspbury, F. Yakhou-Harris, P. van der Linden, N. B. Brookes
Journal of Synchrotron Radiation 23, 464 (2016). DOI