Helicity-dependent resonant X-ray scattering in CuB2O4.
E N Ovchinnikova1, A Rogalev2, F Wilhelm2
1Physics Department, Moscow State University, Moscow 119899, Russia.
Journal of Synchrotron Radiation
|September 3, 2021
Summary
Circular dichroism in X-ray diffraction reveals new insights into forbidden Bragg reflections in non-centrosymmetric crystals. This study observed helicity-dependent resonant diffraction in copper metaborate, highlighting Cu atom contributions.
Area of Science:
- Condensed matter physics
- Materials science
- Crystallography
Background:
- Forbidden Bragg reflections offer unique crystallographic information.
- X-ray circular dichroism (XCD) can probe element-specific magnetic and electronic properties.
- Studying non-centrosymmetric crystals is crucial for understanding phenomena like ferroelectricity and piezoelectricity.
Purpose of the Study:
- To explore the potential of X-ray circular polarized beams for studying forbidden Bragg reflections.
- To investigate helicity-dependent resonant diffraction in the non-centrosymmetric copper metaborate (CuB2O4) single crystal.
- To determine the origin of circular dichroism in forbidden reflections at the Cu K-edge.
Main Methods:
- Utilizing X-ray circular polarized beams for diffraction experiments.
- Analyzing forbidden Bragg reflections in CuB2O4.
- Resonant diffraction measurements near the Copper K-edge.
Main Results:
- Observed significant circular dichroism in hh0 forbidden reflections.
- Demonstrated that the intensity difference between right- and left-circular polarizations is dependent on helicity.
- Attributed the observed circular dichroism to dipolar transitions involving Cu atoms at the 8(d) Wyckoff position.
Conclusions:
- X-ray circular dichroism is a powerful tool for investigating forbidden reflections in non-centrosymmetric crystals.
- The study provides new insights into the electronic structure and atomic contributions to resonant diffraction in CuB2O4.
- This technique can be extended to study other non-centrosymmetric materials with potential applications in advanced electronic devices.
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