Spin-resolved NEXAFS from resonant X-ray scattering (RXS)

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spectroscopy

Background:

• Resonantly excited metal K core line spectra provide insights into electronic structure.
• Understanding spin states in magnetic and non-magnetic materials is crucial.

Purpose of the Study:

• To investigate spin conservation in resonant X-ray scattering.
• To develop a novel technique for quantitative resolution of NEXAFS spectra into spin-up and spin-down components.
• To apply this method to paramagnetic MnO.

Main Methods:

• Utilized beamlines X21 (NSLS/BNL) and BW1, W1.1 (HASYLAB/DESY) for spectral data acquisition.
• Analyzed spectral data based on spin conservation and local spin references.
• Employed angular-dependent measurements on single-crystal samples to utilize linear dichroism.

Main Results:

• Confirmed spin conservation in resonant scattering below and above the absorption threshold.
• Observed distinct absorption thresholds for spin-up and spin-down components.
• Demonstrated the importance of quadrupole transitions in the excitation process.
• Successfully resolved NEXAFS spectra into spin-up and spin-down components without circularly polarized radiation or sample magnetization.
• Obtained unambiguous experimental results for paramagnetic MnO, confirming theoretical calculations.

Conclusions:

• A novel, magnetization-free technique for quantitative spin resolution of NEXAFS spectra has been developed.
• The method is applicable to a wide range of materials, including antiferromagnetic and paramagnetic compounds.
• NEXAFS spectra of MnO show predominantly spin-down character for metal K pre-edge XAS and spin-up character for delocalized p-like states.