Decay of semiclassical massless Dirac fermions from integrable and chaotic cavities

Chen Di Han, Cheng Zhen Wang, Hong Ya Xu, Danhong Huang, Ying-Cheng Lai

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Conventional microlasing of electromagnetic waves requires (1) a high-Q cavity and (2) a mechanism for directional emission. Previous theoretical and experimental work demonstrated that the two requirements can be met with deformed dielectric cavities that generate chaotic ray dynamics. Is it possible for a massless Dirac spinor wave in graphene or its photonic counterpart to exhibit a similar behavior? Intuitively, because of the absence of backscattering of associated massless spin-1/2 particles and Klein tunneling, confining the wave in a cavity for a long time seems not feasible. Deforming the cavity to generate classical chaos would make confinement even more difficult. Investigating the decay of a spin-1/2 wave from a scalar potential barrier-defined cavity characterized by an effective refractive index n that depends on the applied potential and the particle energy, we uncover the striking existence of an interval of the refractive index in which the average lifetime of the massless spin-1/2 wave in the cavity can be as high as that of the electromagnetic wave for both integrable and chaotic cavities. We also find scaling laws for the ratio between the mean escape time associated with electromagnetic waves and that with massless spin-1/2 particles versus the index outside of this interval. The scaling laws hold regardless of the nature of the classical dynamics. All the results are verified numerically. The findings provide insight into the emergent field of Dirac electron optics and have potential applications in developing unconventional electronics using two-dimensional Dirac materials.

Original languageEnglish (US)
Article number104308
JournalPhysical Review B
Volume98
Issue number10
DOIs
StatePublished - Sep 18 2018

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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