Gapless MoS2] allotrope possessing both massless Dirac and heavy fermions

Article

关键词: TOTAL-ENERGY CALCULATIONS;    WAVE BASIS-SET;    TOPOLOGICAL INSULATORS;    MOLYBDENUM-DISULFIDE;    GRAIN-BOUNDARIES;    GRAPHENE;    NANOSHEETS;    MONOLAYER;    SILICON;   

DOI  :  10.1103/PhysRevB.89.205402

来源: SCIE

【 摘 要 】

MoS2, a member of transition metal dichalcogenides (TMDs), has recently emerged as an interesting two-dimensional material due to its unique mechanical, thermal, electronic and optical properties. Unlike graphene which possesses massless Dirac fermions with ultrahigh electron mobility, monolayer MoS2 is a direct band gap semiconductor. An interesting question arises: Can monolayer MoS2 also possess massless Dirac fermions with ultrahigh electron mobility? Here, using first-principles calculations, we show that a monolayer MoS2 allotrope, which consists of repeated square-octagon rings (abbreviated as so-MoS2 to distinguish it from the normal hexagonal lattice, h-MoS2) possesses bothmassless Dirac fermions and heavy fermions. Distinct from the p-orbital Dirac fermions of graphene, the Dirac fermions of so-MoS2 are d electrons and possess a Fermi velocity comparable to that of graphene. The Dirac cone structure in so-MoS2 demonstrated here greatly enriches our understanding on the physical properties of TMDs and opens up possibilities for developing high-performance electronic or spintronic devices.

【 授权许可】

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