CeCoSi隐秩序相中电子结构改变的观测
Observation of Electronic Structure Modification in the Hidden Order Phase of CeCoSi
AI总结：
本文利用高精度光学反射光谱观测CeCoSi在隐秩序相变前后的电子结构，发现低温相费米能级附近出现约15 meV类能隙，并将其归因于电子/价态不稳定性。
摘要：
CeCoSi不具有局部反演对称晶体结构（$P4/nmm$），在反铁磁转变温度（$T_{\ m N}=9.4$ K）以上约12 K（$T_0$）处表现出一种起源未知的相变（隐秩序：HO）。本研究采用高精度光学反射光谱研究了跨越$T_0$的电子结构变化。光谱从$T_0$以上的典型金属性行为转变为$T_0$以下约15 meV处的类能隙结构。该类能隙结构在跨越$T_{\ m N}$时保持不变，仅因磁涨落受到抑制而使载流子的Drude分量变窄。该结果表明，电子结构从$T_0$以上的典型金属性电子结构轻微转变为HO相中费米能级附近具有能隙的电子结构。研究结论认为，HO相中电子结构的变化源于电子/价态不稳定性。
英文摘要：
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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