A versatile X-ray phase retarder for lock-in XMCD measurements

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spectroscopy

Background:

• X-ray magnetic circular dichroism (XMCD) is crucial for element and orbital selective magnetic property analysis.
• Traditional XMCD often requires alternating magnetic field or X-ray polarization, impacting data reliability and acquisition speed.
• Achieving high-quality XMCD data necessitates efficient generation and manipulation of circularly polarized (CP) X-rays.

Purpose of the Study:

• To develop a versatile strategy for performing XMCD experiments with improved efficiency and data quality.
• To implement a method utilizing a hard X-ray quarter-wave plate for alternating X-ray helicity.
• To demonstrate the effectiveness of this new instrumentation for magnetic property characterization.

Main Methods:

• A novel XMCD strategy was developed using a hard X-ray quarter-wave plate.
• Experiments were conducted using both polychromatic dispersive and conventional monochromatic optics.
• Synchronous data acquisition and a lock-in amplifier were employed to process the XMCD signal.
• The beam helicity was switched at 13 Hz, generating 98% CP X-rays.

Main Results:

• The developed instrumentation successfully generated 98% circularly polarized X-rays.
• The new method demonstrated improved data quality and reduced acquisition time compared to conventional techniques.
• XMCD experiments were performed effectively using both polychromatic and monochromatic X-ray optics.
• The system showed potential for even faster helicity switching at future facilities like SIRIUS.

Conclusions:

• A versatile and efficient strategy for XMCD experiments has been successfully implemented.
• The use of a hard X-ray quarter-wave plate significantly enhances data quality and acquisition speed.
• This technique offers a reliable method for probing magnetic properties of materials with high element and orbital selectivity.
• The developed instrumentation is well-suited for advanced synchrotron facilities, enabling next-generation magnetic material research.