中国物理B ›› 2026, Vol. 35 ›› Issue (7): 76801-076801.doi: 10.1088/1674-1056/ae6568

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Cascade of low-energy surface phonon modes on the B-terminated EuB6 surface

Yumeng Li(李雨萌)1,2,†, Meng Li(李萌)1,2,†, Lijing Huang(黄丽静)1,2,†, Haitao Yang(杨海涛)1,2,3, Hongqin Xiao(肖洪钦)1,2, Yuxuan He(何昱萱)1,2, Geng Li(李更)1,2,3,‡, and Hong-Jun Gao(高鸿钧)1,2,3   

  1. 1 Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China;
    3 Hefei National Laboratory, Hefei 230088, China
  • 收稿日期:2026-03-26 修回日期:2026-04-17 接受日期:2026-04-28 发布日期:2026-07-10
  • 通讯作者: Geng Li E-mail:gengli.iop@iphy.ac.cn
  • 基金资助:
    The work is supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1207702 and 2022YFA1204100), the National Natural Science Foundation of China (Grant No. 62488201), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-003), and the Quantum Science and Technology-National Science and Technology Major Project (Grant No. 2021ZD0302700).

Cascade of low-energy surface phonon modes on the B-terminated EuB6 surface

Yumeng Li(李雨萌)1,2,†, Meng Li(李萌)1,2,†, Lijing Huang(黄丽静)1,2,†, Haitao Yang(杨海涛)1,2,3, Hongqin Xiao(肖洪钦)1,2, Yuxuan He(何昱萱)1,2, Geng Li(李更)1,2,3,‡, and Hong-Jun Gao(高鸿钧)1,2,3   

  1. 1 Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China;
    3 Hefei National Laboratory, Hefei 230088, China
  • Received:2026-03-26 Revised:2026-04-17 Accepted:2026-04-28 Published:2026-07-10
  • Contact: Geng Li E-mail:gengli.iop@iphy.ac.cn
  • Supported by:
    The work is supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1207702 and 2022YFA1204100), the National Natural Science Foundation of China (Grant No. 62488201), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-003), and the Quantum Science and Technology-National Science and Technology Major Project (Grant No. 2021ZD0302700).

摘要: EuB$_{6}$ has emerged as a leading candidate magnetic Weyl semimetal, in which spontaneous ferromagnetic order breaks time-reversal symmetry and drives a topological phase transition accompanied by band inversion. Optical studies have extensively investigated the phonon modes associated with the B$_{6}$ octahedra, whose internal vibrations play an important role in understanding the physical properties of EuB$_{6}$. However, the low-energy phonon modes and their coupling to electrons remain largely unexplored. Here we report a cascade of low-energy phonon modes resolved on the B-terminated surface of EuB$_{6}$ prepared by low-temperature in situ cleavage. We show that defects significantly modulate the local electron-phonon coupling (EPC) strength. Moreover, a defect-pinned $\sqrt {2} \times \sqrt {2} $ short-range order emerges on the B-terminated surface, which selectively modulates the local density of states (LDOS) and the EPC strength. Our results provide insight into the interplay between low-energy surface phonons, defects, and electron-phonon coupling on the B-terminated surface of EuB$_{6}$.

关键词: EuB6, inelastic electron tunneling spectroscopy, surface phonons, electron-phonon coupling, short-range order

Abstract: EuB$_{6}$ has emerged as a leading candidate magnetic Weyl semimetal, in which spontaneous ferromagnetic order breaks time-reversal symmetry and drives a topological phase transition accompanied by band inversion. Optical studies have extensively investigated the phonon modes associated with the B$_{6}$ octahedra, whose internal vibrations play an important role in understanding the physical properties of EuB$_{6}$. However, the low-energy phonon modes and their coupling to electrons remain largely unexplored. Here we report a cascade of low-energy phonon modes resolved on the B-terminated surface of EuB$_{6}$ prepared by low-temperature in situ cleavage. We show that defects significantly modulate the local electron-phonon coupling (EPC) strength. Moreover, a defect-pinned $\sqrt {2} \times \sqrt {2} $ short-range order emerges on the B-terminated surface, which selectively modulates the local density of states (LDOS) and the EPC strength. Our results provide insight into the interplay between low-energy surface phonons, defects, and electron-phonon coupling on the B-terminated surface of EuB$_{6}$.

Key words: EuB6, inelastic electron tunneling spectroscopy, surface phonons, electron-phonon coupling, short-range order

中图分类号:  (Structure of clean surfaces (and surface reconstruction))

  • 68.35.B-
68.35.Ja (Surface and interface dynamics and vibrations) 63.20.kd (Phonon-electron interactions) 68.37.Ef (Scanning tunneling microscopy (including chemistry induced with STM)) 64.60.Cn (Order-disorder transformations)