Realization of a two-dimensional Weyl semimetal and topological Fermi strings

Qiangsheng Lu; P V Sreenivasa Reddy; Hoyeon Jeon; Alessandro R Mazza; Matthew Brahlek; Weikang Wu; Shengyuan A Yang; Jacob Cook; Clayton Conner; Xiaoqian Zhang; Amarnath Chakraborty; Yueh-Ting Yao; Hung-Ju Tien; Chun-Han Tseng; Po-Yuan Yang; Shang-Wei Lien; Hsin Lin; Tai-Chang Chiang; Giovanni Vignale; An-Ping Li; Tay-Rong Chang; Rob G Moore; Guang Bian

doi:10.1038/s41467-024-50329-6

Realization of a two-dimensional Weyl semimetal and topological Fermi strings

Nat Commun. 2024 Jul 17;15(1):6001. doi: 10.1038/s41467-024-50329-6.

Authors

Qiangsheng Lu^#^{1

2}, P V Sreenivasa Reddy^#³, Hoyeon Jeon^#⁴, Alessandro R Mazza^{2

5}, Matthew Brahlek², Weikang Wu⁶, Shengyuan A Yang⁶, Jacob Cook¹, Clayton Conner¹, Xiaoqian Zhang¹, Amarnath Chakraborty¹, Yueh-Ting Yao³, Hung-Ju Tien³, Chun-Han Tseng³, Po-Yuan Yang³, Shang-Wei Lien³, Hsin Lin⁷, Tai-Chang Chiang^{8

9}, Giovanni Vignale¹, An-Ping Li¹⁰, Tay-Rong Chang^{11

12

13}, Rob G Moore¹⁴, Guang Bian^{15

16}

Affiliations

¹ Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA.
² Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
³ Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan.
⁴ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁵ Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
⁶ Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore.
⁷ Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
⁸ Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL, 61801-3080, USA.
⁹ Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Avenue, Urbana, IL, 61801-2902, USA.
¹⁰ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. [email protected].
¹¹ Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan. [email protected].
¹² Center for Quantum Frontiers of Research and Technology (QFort), Tainan, 70101, Taiwan. [email protected].
¹³ Physics Division, National Center for Theoretical Sciences, Taipei, 10617, Taiwan. [email protected].
¹⁴ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. [email protected].
¹⁵ Department of Physics and Astronomy, University of Missouri, Columbia, MO, 65211, USA. [email protected].
¹⁶ MU Materials Science & Engineering Institute, University of Missouri, Columbia, MO, 65211, USA. [email protected].

^# Contributed equally.

Abstract

A two-dimensional (2D) Weyl semimetal, akin to a spinful variant of graphene, represents a topological matter characterized by Weyl fermion-like quasiparticles in low dimensions. The spinful linear band structure in two dimensions gives rise to distinctive topological properties, accompanied by the emergence of Fermi string edge states. We report the experimental realization of a 2D Weyl semimetal, bismuthene monolayer grown on SnS(Se) substrates. Using spin and angle-resolved photoemission and scanning tunneling spectroscopies, we directly observe spin-polarized Weyl cones, Weyl nodes, and Fermi strings, providing consistent evidence of their inherent topological characteristics. Our work opens the door for the experimental study of Weyl fermions in low-dimensional materials.

Abstract

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