Dirac cones in isogonal hexagonal metallic structures

作     者：Kang Wang 

作者机构：Laboratoire de Physique des Solides UMR CNRS/Université Paris-Sud Université Paris-Saclay 91405 Orsay France 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第12期

页      面：125146-125146页

核心收录：

主　　题：Photonics Honeycomb lattice Polarization Band structure methods Finite-difference time-domain method 

摘      要：A honeycomb hexagonal metallic lattice is equivalent to a triangular atomic one and cannot create Dirac cones in its electromagnetic wave spectrum. We study in this work the low-frequency electromagnetic band structures in isogonal hexagonal metallic lattices that are directly related to the honeycomb one and show that such structures can create Dirac cones. The band formation can be described by a tight-binding model that allows investigating, in terms of correlations between local resonance modes, the condition for the Dirac cones and the consequence of the third structure tile sustaining an extra resonance mode in the unit cell that induces band shifts and thus nonlinear deformation of the Dirac cones following the wave vectors departing from the Dirac points. We show further that, under structure deformation, the deformations of the Dirac cones result from two different correlation mechanisms, both reinforced by the lattice s metallic nature, which directly affects the resonance mode correlations. The isogonal structures provide new degrees of freedom for tuning the Dirac cones, allowing adjustment of the cone shape by modulating the structure tiles at the local scale without modifying the lattice periodicity and symmetry.