中国物理B ›› 2026, Vol. 35 ›› Issue (5): 57110-057110.doi: 10.1088/1674-1056/ae41a2

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Porous-B18: An ideal topological semimetal with symmetry-enforced orthogonal nodal-line and nodal-surface states

Xiao-Jing Gao(高晓晶), Yanfeng Ge(盖彦峰), and Yan Gao(高炎)†   

  1. State Key Laboratory of Metastable Materials Science and Technology & Hebei Key Laboratory of Microstructural Material Physics, School of Science, Yanshan University, Qinhuangdao 066004, China
  • 收稿日期:2025-12-13 修回日期:2026-01-01 接受日期:2026-02-04 发布日期:2026-05-15
  • 通讯作者: Yan Gao E-mail:yangao9419@ysu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 12304202), the Natural Science Foundation of Hebei Province, China (Grant No. A2023203007), the Science Research Project of Hebei Education Department (Grant No. BJK2024085), and the Cultivation Project for Basic Research and Innovation of Yanshan University (No. 2022LGZD001).

Porous-B18: An ideal topological semimetal with symmetry-enforced orthogonal nodal-line and nodal-surface states

Xiao-Jing Gao(高晓晶), Yanfeng Ge(盖彦峰), and Yan Gao(高炎)†   

  1. State Key Laboratory of Metastable Materials Science and Technology & Hebei Key Laboratory of Microstructural Material Physics, School of Science, Yanshan University, Qinhuangdao 066004, China
  • Received:2025-12-13 Revised:2026-01-01 Accepted:2026-02-04 Published:2026-05-15
  • Contact: Yan Gao E-mail:yangao9419@ysu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 12304202), the Natural Science Foundation of Hebei Province, China (Grant No. A2023203007), the Science Research Project of Hebei Education Department (Grant No. BJK2024085), and the Cultivation Project for Basic Research and Innovation of Yanshan University (No. 2022LGZD001).

摘要: Topological semimetals (TSMs) featuring symmetry-protected band degeneracies have attracted considerable attention due to their exotic quantum properties and potential applications. While nodal line (NL) and nodal surface (NS) semimetals have been extensively studied, the realization of a material where both NL and NS coexist and are intertwined, particularly with an ideal electronic band structure, remains a significant challenge. Here, we predict via first-principles calculations and symmetry analysis a metastable boron allotrope, porous-B$_{18}$ (space group $P6_3/m$, No. 176), as a pristine TSM hosting a NS and two straight NLs near the Fermi level. The structure, a honeycomb-like porous 3D framework, exhibits excellent dynamical, thermal (stable up to 1000 K), and mechanical stability. Its electronic band structure is remarkably clean: only the highest valence band (HVB) and the lowest conduction band (LCB) cross linearly within a large energy window of 1.84 eV, free from trivial-band interference. The nodal surface lies on the $k_z = \pm \pi$ planes, protected by combined time-reversal symmetry ($T$) and twofold screw-rotational symmetry ($S_{2z}$), yielding a full-plane Kramers-like degeneracy. The two nodal lines along $K$-$H$ and $K'$-$H'$ are protected by inversion and time-reversal symmetries, carry a quantized Berry phase of $\pm \pi$, and connect orthogonally to the nodal surface, forming an intertwined nodal network. Drumhead surface states on the $(1\bar{1}0)$ surface further confirm the nontrivial topology. Porous-B$_{18}$ thus provides an ideal platform for investigating the interplay between nodal-line and nodal-surface fermions and exploring novel quantum transport phenomena.

关键词: topological semimetal, nodal line, nodal surface, boron allotrope, first-principles calculations

Abstract: Topological semimetals (TSMs) featuring symmetry-protected band degeneracies have attracted considerable attention due to their exotic quantum properties and potential applications. While nodal line (NL) and nodal surface (NS) semimetals have been extensively studied, the realization of a material where both NL and NS coexist and are intertwined, particularly with an ideal electronic band structure, remains a significant challenge. Here, we predict via first-principles calculations and symmetry analysis a metastable boron allotrope, porous-B$_{18}$ (space group $P6_3/m$, No. 176), as a pristine TSM hosting a NS and two straight NLs near the Fermi level. The structure, a honeycomb-like porous 3D framework, exhibits excellent dynamical, thermal (stable up to 1000 K), and mechanical stability. Its electronic band structure is remarkably clean: only the highest valence band (HVB) and the lowest conduction band (LCB) cross linearly within a large energy window of 1.84 eV, free from trivial-band interference. The nodal surface lies on the $k_z = \pm \pi$ planes, protected by combined time-reversal symmetry ($T$) and twofold screw-rotational symmetry ($S_{2z}$), yielding a full-plane Kramers-like degeneracy. The two nodal lines along $K$-$H$ and $K'$-$H'$ are protected by inversion and time-reversal symmetries, carry a quantized Berry phase of $\pm \pi$, and connect orthogonally to the nodal surface, forming an intertwined nodal network. Drumhead surface states on the $(1\bar{1}0)$ surface further confirm the nontrivial topology. Porous-B$_{18}$ thus provides an ideal platform for investigating the interplay between nodal-line and nodal-surface fermions and exploring novel quantum transport phenomena.

Key words: topological semimetal, nodal line, nodal surface, boron allotrope, first-principles calculations

中图分类号:  (Electron density of states and band structure of crystalline solids)

  • 71.20.-b
73.20.At (Surface states, band structure, electron density of states) 71.90.+q (Other topics in electronic structure)