カゴメ超伝導体CsV₃Sb₅におけるエキゾチック準粒子状態の観測(Researchers Observe Exotic Quasiparticle States in Kagome Superconductor CsV3Sb5)

2026-04-02 合肥物質科学研究院(HFIPS)

中国科学院合肥物質科学研究院の郝寧教授らの研究チームは、カゴメ型超伝導体CsV3Sb5において、単一原子不純物を量子プローブとして用い、2種類の特異な低エネルギー準粒子状態を観測した。走査トンネル分光により、磁性クロム原子では鏡映対称性を破る近藤共鳴が確認され、カイラル電流秩序の可能性が示唆された。また、バナジウム欠損近傍ではゼロバイアス伝導ピークが観測され、超伝導秩序の局所振動に起因し、トポロジカル表面状態下ではマヨラナ零モードとの関連が示された。これにより欠陥誘起励起と超伝導機構理解に新たな知見が得られた。

カゴメ超伝導体CsV₃Sb₅におけるエキゾチック準粒子状態の観測(Researchers Observe Exotic Quasiparticle States in Kagome Superconductor CsV3Sb5)
a, Kondo state near a Cr atom with complete breaking of spatial symmetry. b, Zero-bias conductance peak induced by a V vacancy. (Image by XIAO Yuhang)

<関連情報>

カゴメ超伝導体における対称性の破れた近藤遮蔽とゼロエネルギーモード Symmetry-broken Kondo screening and zero-energy mode in a kagome superconductor

Yubing Tu,Zongyuan Zhang,Wenjian Lu,Yuhang Xiao,Tao Han,Run Lv,Zhuying Wang,Zekun Zhou,Xingyuan Hou,Ning Hao,Zhenyu Wang,Xianhui Chen & Lei Shan
Nature Physics  Published:24 March 2026
DOI:https://doi.org/10.1038/s41567-026-03223-5

Abstract

Quantum states of matter reorganize themselves in response to defects, giving rise to emergent local excitations that reflect the intrinsic properties of the underlying phases. Magnetic impurities, for example, generate Kondo screening in a Fermi liquid and Yu–Shiba–Rusinov states in a conventional superconductor. Yet, it remains unclear whether such impurities can trigger unconventional phenomena in the kagome superconductor AV3Sb5, where A represents K, Rb or Cs, which hosts a putative loop current order intertwined with its charge density wave. Here we demonstrate the emergence of Kondo resonance states near magnetic dopants in CsV3Sb5. Using scanning tunnelling microscopy, we find that the spatial structure of the Kondo screening near magnetic Cr impurities breaks all in-plane mirror symmetries of the kagome lattice. This symmetry breaking suggests the presence of an underlying electronic chirality arising from the proposed orbital loop current order. We also observe a pronounced zero-bias conductance peak arising from weakly magnetic V vacancies. These results provide insight into the coexistence and interplay of quantum states in kagome lattice compounds.

1701物理及び化学
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