Directional massless Dirac fermions in a layered van der Waals material with one-dimensional long-range order

Abstract

Exotic properties in single or few layers of van der Waals materials carry great promise for applications in nanoscaled electronics, optoelectronics and flexible devices. The established, distinct examples include extremely high mobility and superior thermal conductivity in graphene, a large direct band gap in monolayer MoS2 and quantum spin Hall effect in WTe2 monolayer, etc. All these exotic properties arise from the electron quantum confinement effect in the two-dimensional limit. Here we report a novel phenomenon due to one-dimensional (1D) confinement of carriers in a layered van der Waals material NbSi0.45Te2 revealed by angle-resolved photoemission spectroscopy, i.e. directional massless Dirac fermions. The 1D behavior of the carriers is directly related to a stripe-like structural modulation with the long-range translational symmetry only along the stripe direction, as perceived by scanning tunneling microscopy experiment. The four-fold degenerated node of 1D Dirac dispersion is essential and independent on band inversion, because of the protection by nonsymmorphic symmetry of the stripe structure. Our study not only provides a playground for investigating the striking properties of the essential directional massless Dirac fermions, but also introduces a unique monomer with 1D long-range order for engineering nano-electronic devices based on heterostructures of layered van der Waals materials.

A revised version published in Nature Materials (2019); 20 pages, 4 figures

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Cited by in corpus (9)

• Observation of one-dimensional Dirac fermions in silicon nanoribbons
• Berry curvature dipole and nonlinear Hall effect in two-dimensional Nb${}_{2n+1}$Si${}_n$Te${}_{4n+2}$
• Inherited Weak Topological Insulator Signatures in Topological Hourglass Semimetal Nb3XTe6 (X = Si, Ge)
• Plasmons in a two-dimensional nonsymmorphic nodal-line semimetal
• Effects of spatial dimensionality and band tilting on the longitudinal optical conductivities in Dirac bands
• Flat bands and temperature-driven phase transition in quasi-one-dimensional zigzag chains
• Nonlinear Optical Spectroscopy of Nodal-Line Semimetals
• Stability of the smectic phase in arrays of parallel quantum wires
• Robust Luttinger liquid state of 1D Dirac fermions in a van der Waals system Nb${}_9$Si${}_4$Te${}_{18}$