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Angle-dependent Ni2+ X-ray magnetic linear dichroism: interfacial coupling revisited
Elke Arenholz1, Gerrit van der Laan, Rajesh V Chopdekar
1Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. earenholz@lbl.gov
Physical Review Letters
|August 7, 2007
Summary
X-ray magnetic linear dichroism (XMLD) spectroscopy for nickel requires two fundamental spectra, not one, for accurate magnetometry. This finding clarifies nickel spectra and reveals perpendicular coupling in Co/NiO interfaces.
Area of Science:
- Solid State Physics
- Materials Science
- Magnetism
Background:
- X-ray magnetic linear dichroism (XMLD) is a powerful technique for probing magnetic properties.
- Accurate magnetometry using XMLD necessitates understanding its dependence on polarization, magnetic moments, and crystal structure.
Purpose of the Study:
- To re-evaluate the description of Ni2+ L(2,3) XMLD spectra in cubic lattices.
- To develop a more accurate model for XMLD analysis in magnetic materials.
- To investigate magnetic coupling at Co/NiO interfaces.
Main Methods:
- Calculation of Ni2+ L(2,3) XMLD spectra using atomic multiplet theory.
- Derivation of angular dependence from crystal field symmetry.
- Application of the refined model to Co/NiO(001) interfaces.
Main Results:
- Ni2+ L(2,3) XMLD in cubic lattices is described by a linear combination of two fundamental spectra, contrary to previous single-spectrum assumptions.
- The study provides a theoretical framework for analyzing XMLD spectra based on crystal field symmetry.
- Perpendicular coupling between Ni and Co magnetic moments was observed at Co/NiO(001) interfaces.
Conclusions:
- The findings necessitate a revision of XMLD spectral analysis for nickel-containing cubic materials.
- The developed model enhances the accuracy of magnetometry using XMLD.
- The discovery of perpendicular coupling provides crucial insights into interfacial magnetism.
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