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Updated: Jun 8, 2026
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Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Raman Optical Activity Induced by Ferroaxial Order in NiTiO_{3}
Gakuto Kusuno1, Takeshi Hayashida2,3, Takayuki Nagai2
1Institute of Science Tokyo, Department of Physics, Tokyo 152-8551, Japan.
Physical Review Letters
|June 7, 2026
Summary
Raman optical activity (ROA) is now observed in ferroaxial crystals, not just chiral molecules. This discovery reveals ROA as a new tool for studying ferroaxial order in centrosymmetric materials.
Area of Science:
- Condensed matter physics
- Spectroscopy
- Materials science
Background:
- Raman optical activity (ROA) traditionally requires broken inversion or time-reversal symmetry, observed in chiral molecules and magnetic materials.
- Ferroaxial crystals are centrosymmetric and nonmagnetic, lacking these traditional symmetry-breaking requirements.
Purpose of the Study:
- To investigate the presence and origin of ROA in centrosymmetric ferroaxial crystals.
- To establish ROA as a viable technique for probing ferroaxial order.
Main Methods:
- Circularly polarized Raman spectroscopy on single-crystalline NiTiO_{3}.
- Symmetry analysis.
- First-principles calculations of phonons.
- Tight-binding model calculations.
Main Results:
- A pronounced ROA signal was observed in NiTiO_{3} in cross-circular polarization configurations.
- The ROA signal directly correlates with the ferroaxial domain structure.
- Theoretical analysis confirmed that ROA originates from ferroaxial order and is independent of electric dipole approximation.
Conclusions:
- ROA can arise in centrosymmetric, nonmagnetic ferroaxial crystals.
- Ferroaxial order is the source of this natural ROA.
- ROA is a powerful new probe for studying ferroaxial order in such systems.
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