Pyramids and cootie catchers: new massless fermions in 2D materials

Abstract

Dirac-like electronic states are the main engines powering the tremendous advances in research of graphene, topological insulators and other materials with these states. Zero effective mass, high carrier mobility and numerous applications are some consequences of linear dispersion that distinguishes Dirac states. Here we report a new class of linear electronic bands in two-dimensional materials with zero effective mass and sharp band edges never seen in solid state matter before, and predict stable materials with such electronic structure utilizing symmetry group analysis and ab initio approach. We make a full classification of completely linear bands in two-dimensional materials and find that only two classes exist: Dirac fermions on one hand and pyramidal-like and cootie catcher-like states on the other hand. The new class supports zero effective mass and hence high carrier mobility similar to that of graphene, anisotropic electronic properties like that of phosphorene, and robustness of states with respect to electronic correlations.

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Cited by in corpus (5)

• Two-dimensional topological semimetals
• Fully linear band crossings at high symmetry points in layers: classification and role of spin-orbit coupling and time reversal
• Electronic structures near unmovable nodal points and lines in two-dimensional materials
• Movable but unavoidable nodal lines through high-symmetry points in two-dimensional materials
• Non-magnetic layers with a single Dirac cone at high-symmetry point of the Brillouin zone