Quasienergy spectra of a charged particle in planar honeycomb lattices

TL;DR

This paper investigates how a strong AC field affects the quasienergy spectra of a charged particle in honeycomb lattices, revealing phenomena like band collapse, velocity renormalization, and phase transitions.

Contribution

It provides the first detailed analysis of quasienergy spectra in driven honeycomb lattices, highlighting new phase transition behaviors and spectral modifications.

Findings

Observation of band collapse and velocity renormalization.

Identification of phase transitions between gapped and gapless states.

Possible experimental realization in honeycomb optical lattices.

Abstract

The low energy spectrum of a particle in planar honeycomb lattices is conical, which leads to the unusual electronic properties of graphene. In this letter we calculate the quasienergy spectra of a charged particle in honeycomb lattices driven by a strong AC field, which is of fundamental importance for its time-dependent dynamics. We find that depending on the amplitude, direction and frequency of external field, many interesting phenomena may occur, including band collapse, renormalization of velocity of ``light'', gap opening etc.. Under suitable conditions, with increasing the magnitude of the AC field, a series of phase transitions from gapless phases to gapped phases appear alternatively. At the same time, the Dirac points may disappear or change to a line. We suggest possible realization of the system in Honeycomb optical lattices.