中国物理B ›› 2026, Vol. 35 ›› Issue (8): 87102-087102.doi: 10.1088/1674-1056/ae69c6

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Observation of layer-dependent uniaxial charge density wave in a noble metal alloy superconductor β-IrSn4

Xiao Liu(刘潇)1,2,†, Geng Li(李更)1,2,3,†,‡, Shiwei Diao(刁世伟)4,†, Haisen Liu(刘海森)1,2, Zhen Zhao (赵振)1,2, Haitao Yang(杨海涛)1,2,3, Lizhi Zhang(张礼智)4,§, Xiao Lin(林晓)1,¶, and Hong-Jun Gao(高鸿钧)1,2,3   

  1. 1 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China;
    2 Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 Hefei National Laboratory, Hefei 230088, China;
    4 Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
  • 收稿日期:2026-04-08 修回日期:2026-04-26 接受日期:2026-05-07 发布日期:2026-07-23
  • 通讯作者: Geng Li, Lizhi Zhang, Xiao Lin E-mail:gengli.iop@iphy.ac.cn;zhanglz@nanoctr.cn;xlin@ucas.ac.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1207700, 2024YFA1207800, and 2022YFA1204100), the National Natural Science Foundation of China (Grant Nos. 62488201, 61925111, and U23A6015), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-003), the Youth Innovation Promotion Association (Grant No. 2023005), and the Quantum Science and Technology-National Science and Technology Major Project (Grant No. 2021ZD0302700).

Observation of layer-dependent uniaxial charge density wave in a noble metal alloy superconductor β-IrSn4

Xiao Liu(刘潇)1,2,†, Geng Li(李更)1,2,3,†,‡, Shiwei Diao(刁世伟)4,†, Haisen Liu(刘海森)1,2, Zhen Zhao (赵振)1,2, Haitao Yang(杨海涛)1,2,3, Lizhi Zhang(张礼智)4,§, Xiao Lin(林晓)1,¶, and Hong-Jun Gao(高鸿钧)1,2,3   

  1. 1 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China;
    2 Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 Hefei National Laboratory, Hefei 230088, China;
    4 Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
  • Received:2026-04-08 Revised:2026-04-26 Accepted:2026-05-07 Published:2026-07-23
  • Contact: Geng Li, Lizhi Zhang, Xiao Lin E-mail:gengli.iop@iphy.ac.cn;zhanglz@nanoctr.cn;xlin@ucas.ac.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1207700, 2024YFA1207800, and 2022YFA1204100), the National Natural Science Foundation of China (Grant Nos. 62488201, 61925111, and U23A6015), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-003), the Youth Innovation Promotion Association (Grant No. 2023005), and the Quantum Science and Technology-National Science and Technology Major Project (Grant No. 2021ZD0302700).

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摘要： The AB$_{4}$-type intermetallic compounds host a wide range of emergent quantum phenomena, providing a fertile platform for exploring the interplay between crystal structure and electronic orders. Among them, $\beta $-IrSn$_{4}$ has recently attracted attention as a noble-metal-based layered superconductor with weak interlayer coupling and type-I superconductivity. However, its electronic states and possible symmetry-breaking orders remain largely unexplored on the atomic scale. Here, we report the observation of a layer-dependent uniaxial charge density wave (CDW) in $\beta $-IrSn$_{4}$ using ultra-low-temperature scanning tunneling microscopy. The charge order appears as stripe-like modulations that break the in-plane $C_{4}$ symmetry, and its orientation rotates by 90$^\circ$ between adjacent layers. Spectroscopy measurements reveal a homogeneous superconducting gap coexisting with the layer-dependent CDW, with no detectable modulation from the charge order. First-principles calculations suggest that interlayer coupling induces the observed anisotropic electronic structure. These results reveal a layer-dependent symmetry-breaking electronic state in $\beta $-IrSn$_{4}$ and highlight the role of interlayer interactions in shaping its electronic properties.

关键词: charge density wave, layer-dependent, superconductivity, interlayer coupling

Abstract: The AB$_{4}$-type intermetallic compounds host a wide range of emergent quantum phenomena, providing a fertile platform for exploring the interplay between crystal structure and electronic orders. Among them, $\beta $-IrSn$_{4}$ has recently attracted attention as a noble-metal-based layered superconductor with weak interlayer coupling and type-I superconductivity. However, its electronic states and possible symmetry-breaking orders remain largely unexplored on the atomic scale. Here, we report the observation of a layer-dependent uniaxial charge density wave (CDW) in $\beta $-IrSn$_{4}$ using ultra-low-temperature scanning tunneling microscopy. The charge order appears as stripe-like modulations that break the in-plane $C_{4}$ symmetry, and its orientation rotates by 90$^\circ$ between adjacent layers. Spectroscopy measurements reveal a homogeneous superconducting gap coexisting with the layer-dependent CDW, with no detectable modulation from the charge order. First-principles calculations suggest that interlayer coupling induces the observed anisotropic electronic structure. These results reveal a layer-dependent symmetry-breaking electronic state in $\beta $-IrSn$_{4}$ and highlight the role of interlayer interactions in shaping its electronic properties.

Key words: charge density wave, layer-dependent, superconductivity, interlayer coupling

中图分类号:  (Charge-density-wave systems)

  • 71.45.Lr
74.55.+v (Tunneling phenomena: single particle tunneling and STM) 74.70.-b (Superconducting materials other than cuprates) 63.22.Np (Layered systems)