Valley-driven Zitterbewegung in Kekul\'e-distorted graphene

TL;DR

This paper explores how Kekulé-Y distortion in graphene induces valley-driven Zitterbewegung, a quantum oscillatory motion, with potential for experimental observation due to its distinctive properties.

Contribution

It demonstrates that Kekulé-Y distortion couples valley and momentum, leading to a unique Zitterbewegung with lower frequency, expanding understanding of electron dynamics in strained graphene.

Findings

Valley-momentum coupling causes Zitterbewegung in Kekulé-Y graphene.

The Zitterbewegung frequency is smaller than in pristine graphene.

Kekulé-Y graphene is promising for observing Zitterbewegung experimentally.

Abstract

Graphene deposited on top of a Copper(111) substrate may develop a Y-shaped Kekul\'e bond texture (Kekul\'e-Y), locking the momentum of its Dirac fermions with its valley degree of freedom. As a consequence, the valley degeneracy of its band structure is broken, generating an energy dispersion with two nested Dirac cones with different Fermi velocities. In this work, we investigate the dynamics of electronic wave packets in the Kekul\'e-Y superlattice. We show that, as a result of the valley-momentum coupling, a valley-driven oscillatory motion of the wave packets ({\it Zitterbewegung}) could appear, but with a smaller frequency than the {\it Zitterbewegung} effect found pristine graphene. This makes Kekul\'e-Y graphene a compelling candidate for experimental observation of {\it Zitterbewegung} phenomenon in a two-dimensional system.