X-ray magnetic circular dichroism imaging with hard X-rays

Area of Science:

• Materials Science
• Condensed Matter Physics
• X-ray Optics

Background:

• X-ray magnetic circular dichroism (XMCD) is a powerful technique for probing magnetic properties of materials.
• Previous XMCD studies were limited in their ability to generate direct spatial images, particularly in the hard X-ray region.
• Developing advanced imaging techniques is crucial for understanding nanoscale magnetic phenomena.

Purpose of the Study:

• To demonstrate the first successful recording of X-ray polarization-contrast images using XMCD in the hard X-ray region.
• To investigate the feasibility of using XMCD for direct magnetic imaging of materials.
• To characterize the magnetic response of cobalt at specific X-ray energies.

Main Methods:

• Utilized a novel apparatus comprising an X-ray polarizer, double X-ray phase retarders, and a high-spatial-resolution X-ray charge-coupled-device detector.
• Employed a hexagonal-close-packed cobalt polycrystal foil (approx. 4 microns thick) as the sample.
• Recorded XMCD polarization-contrast images at photon energies 10 eV and 32 eV above the cobalt K-absorption edge (7709 eV).

Main Results:

• Successfully obtained the first hard X-ray XMCD polarization-contrast images.
• Observed image contrast reversal upon magnetic field inversion, confirming the XMCD effect.
• Demonstrated a secondary contrast reversal at a different photon energy (32 eV above the absorption edge), indicating energy-dependent magnetic response.

Conclusions:

• The study presents a groundbreaking method for direct hard X-ray magnetic imaging via XMCD.
• The results validate the potential of this technique for detailed characterization of magnetic materials.
• This advancement opens new possibilities for nanoscale magnetic imaging and materials analysis.