Abstract

A topological quantum phase requires a finite momentum-space Berry curvature which, conventionally, can arise through breaking the inversion or the time-reversal symmetry so as to generate nontrivial, topologically invariant quantities associated with the underlying energy band structure (e.g., a finite Chern number). For conventional graphene or graphenelike two-dimensional (2D) systems with gapless Dirac cones, the symmetry breaking will make the system insulating due to lifting of the degeneracy. To design materials that simultaneously possess the two seemingly contradicting properties (i.e., a semimetal phase with gapless bulk Dirac-like cones and a finite Berry curvature) is of interest. We propose a 2D mechanical dice lattice system that exhibits precisely such properties. As a result, an intrinsic valley Hall effect can arise without compromising the carrier mobility as the quasiparticles remain massless. We also find that, with confinement along the zigzag edges, two distinct types of gapless edge states with opposite edge polarizations can arise, one with a finite but the other with zero group velocity.

Original languageEnglish (US)
Article number235159
JournalPhysical Review B
Volume95
Issue number23
DOIs
StatePublished - Jun 30 2017

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metalloids
curvature
cones
carrier mobility
group velocity
energy bands
valleys
Hall effect
broken symmetry
graphene
inversions
momentum
symmetry
polarization

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Mechanical topological semimetals with massless quasiparticles and a finite Berry curvature. / Wang, Guanglei; Xu, Hongya; Lai, Ying-Cheng.

In: Physical Review B, Vol. 95, No. 23, 235159, 30.06.2017.

Research output: Contribution to journalArticle

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