Dynamical freezing and switching in periodically driven bilayer graphene

TL;DR

This paper investigates how periodically driven bilayer graphene exhibits nonmonotonic responses and near-absolute freezing phenomena, extending understanding from simpler models to more complex, multi-band systems, with potential realization in ultracold atom experiments.

Contribution

It demonstrates that bilayer graphene under periodic driving shows nonmonotonic responses and freezing only with a constant bias, extending integrable model insights to multi-band systems.

Findings

Near absolute freezing occurs with a constant bias in the drive.

Freezing is suppressed when the bias is absent.

Analytical support via rotating wave approximation.

Abstract

A class of integrable models, such as the one-dimensional transverse-field Ising model, respond nonmonotonically to a periodic drive with respect to the driving parameters and freezes almost absolutely for certain combinations of the latter. In this paper, we go beyond the two-band structure of the Ising-like models studied previously and ask whether such unusual nonmonotonic response and near-absolute freezing occur in integrable systems with a higher number of bands. To this end, we consider a tight-binding model for bilayer graphene subjected to an interlayer potential difference. We find that when the potential is driven periodically, the system responds nonmonotonically to variations in the driving amplitude $V_0$ and frequency $\omega$ and shows near absolute freezing for certain values of $V_0/\omega$. However, the freezing occurs only in the presence of a constant bias in the driving, i.e., when $V= V'+V_0 \cos{\omega t}$. When $V'=0$, the freezing is switched off for all values of $V_0/\omega$. We support our numerical results with analytical calculations based on a rotating wave approximation. We also give a proposal to realize the driven bilayer system via ultracold atoms in an optical lattice, where the driving can be implemented by shaking the lattice.