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arXiv · 2302.09749

Observation of Electronic Structure Modification in the Hidden Order Phase of CeCoSi

Shin-ichi Kimura·Hiroshi Watanabe·Shingo Tatsukawa·Hiroshi Tanida
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Abstract

CeCoSi with no local inversion symmetric crystal structure ($P4/nmm$) exhibits a phase transition of unknown origin (Hidden Order: HO) at about 12 K ($T_0$) above the antiferromagnetic transition temperature ($T_{\rm N}=9.4$ K). The electronic structure change across $T_0$ was investigated with high-precision optical reflection spectroscopy. The optical spectrum changed from a typical metallic behavior above $T_0$ to a gap-like structure at around 15 meV below $T_0$. The gap-like structure was unchanged across $T_{\rm N}$ except for the narrowing of the Drude component of carriers due to the suppression of magnetic fluctuations. This result suggests a slight change from the typical metallic electronic structure above $T_0$ to that with an energy gap near the Fermi level in the HO phase. The change in electronic structure in the HO phase was concluded to be due to electron/valence instability.

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Shin-ichi Kimura, Hiroshi Watanabe, Shingo Tatsukawa, Hiroshi Tanida. 2023-02-20. Observation of Electronic Structure Modification in the Hidden Order Phase of CeCoSi. https://doi.org/10.7566/jpsj.92.043704

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