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arXiv · 2603.21756

Electric toroidal octupolar symmetry in pyrite FeS$_2$ probed by Raman optical activity

Yuki Suganuma·Gakuto Kusuno·Hikaru Watanabe·Rikuto Oiwa·Hitoshi Mori·Ryotaro Arita·Takuya Satoh
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Abstract

We report Raman optical activity in pyrite FeS$_2$, which hosts an electric toroidal octupolar symmetry. A clear and reproducible sign reversal of the circular intensity difference is observed between neighboring $\{111\}$ faces under cross-circular polarization. The signal appears only for the doubly degenerate $E_g$ phonon mode and is absent for other modes, consistent with symmetry analysis. First-principles calculations reproduce these features, establishing Raman optical activity as a probe of higher-rank axial multipolar symmetry.

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Yuki Suganuma, Gakuto Kusuno, Hikaru Watanabe, Rikuto Oiwa, Hitoshi Mori, Ryotaro Arita, Takuya Satoh. 2026-03-23. Electric toroidal octupolar symmetry in pyrite FeS$_2$ probed by Raman optical activity. https://arxiv.org/abs/2603.21756

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