Magnetic-tunnelling-induced Weyl node annihilation in TaP

Cheng Long Zhang, Su Yang Xu, C. M. Wang, Ziquan Lin, Z. Z. Du, Cheng Guo, Chi Cheng Lee, Hong Lu, Yiyang Feng, Shin Ming Huang, Guoqing Chang, Chuang Han Hsu, Haiwen Liu, Hsin Lin, Liang Li, Chi Zhang, Jinglei Zhang, Xin Cheng Xie, Titus Neupert, M. Zahid HasanHai Zhou Lu, Junfeng Wang, Shuang Jia

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Weyl nodes are topological objects in three-dimensional metals. Whereas the energy of the lowest Landau band of a conventional Fermi pocket increases with magnetic field due to the zero-point energy (1/2[planck]Ï ‰), the lowest Landau band of Weyl cones stays at zero energy unless a strong magnetic field couples Weyl fermions of opposite chirality. In the Weyl semimetal TaP, which possesses two types of Weyl nodes (four pairs of W1 and eight pairs of W2 nodes), we observed such a magnetic coupling between the electron pockets arising from the W1 Weyl fermions. As a result, their lowest Landau bands move above the chemical potential, leading to a sharp sign reversal in the Hall resistivity at a specific magnetic field corresponding to the separation in momentum space of the W1 Weyl nodes,∼Δκ W1 . By contrast, annihilation is not observed for the hole pocket because the separation of the W2 Weyl nodes is much larger. These findings reveal the nontrivial topology of Weyl fermions in high-field transport measurements and demonstrate the observation of Weyl node annihilation, which is a unique topological phenomenon associated with Weyl fermions.

Original languageEnglish (US)
Pages (from-to)979-986
Number of pages8
JournalNature Physics
Issue number10
StatePublished - Oct 4 2017

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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