One or a few layers of van der Waals (vdW) materials are promising for applications in nanoscale electronics. Established properties include high mobility in graphene, a large direct gap in monolayer MoS2, the quantum spin Hall effect in monolayer WTe2 and so on. These exciting properties arise from electron quantum confinement in the two-dimensional limit. Here, we use angle-resolved photoemission spectroscopy to reveal directional massless Dirac fermions due to one-dimensional confinement of carriers in the layered vdW material NbSi0.45Te2. The one-dimensional directional massless Dirac fermions are protected by non-symmorphic symmetry, and emerge from a stripe-like structural modulation with long-range translational symmetry only along the stripe direction as we show using scanning tunnelling microscopy. Our work not only provides a playground for investigating further the properties of directional massless Dirac fermions, but also introduces a unique component with one-dimensional long-range order for engineering nano-electronic devices based on heterostructures of vdW materials.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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This work was supported by the National Key R&D Programme of China (grant nos. 2018FYA0305800, 2016YFA0300403 and 2017YFA0302901), the Ministry of Science and Technology of China (grant no. 2018YFA0307000), the National Natural Science Foundation of China (grant nos. 11874047, 11674226, 11790313 and 11774399), the Fundamental Research Funds for the Central Universities (grant no. 2042018kf-0030), Beijing Natural Science Foundation (grant no. Z180008) and the K. C. Wong Education Foundation (grant no. GJTD-2018-01). Z.Q.M. acknowledges the support by the US Department of Energy under grant no. DE-SC0019068. N.X. acknowledges support by Wuhan University startup funding.
The authors declare no competing interests.
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Yang, T.Y., Wan, Q., Yan, D.Y. et al. Directional massless Dirac fermions in a layered van der Waals material with one-dimensional long-range order. Nat. Mater. 19, 27–33 (2020). https://doi.org/10.1038/s41563-019-0494-1
npj Quantum Materials (2022)