Non-linear effects in the cyclotron resonance of a massless quasi-particle in graphene

TL;DR

This paper investigates how massless quasi-particles in graphene exhibit non-linear cyclotron resonance effects due to their linear energy dispersion, explaining broad resonance linewidths observed experimentally.

Contribution

It demonstrates that linear response theory fails in graphene's finite magnetic fields and highlights the non-linear effects in cyclotron resonance of massless quasi-particles.

Findings

Broad resonance linewidths observed in experiments

Linear response theory is inadequate for graphene in magnetic fields

Non-linear effects generate a wide frequency spectrum

Abstract

We consider the classical motion of a massless quasi-particle in a magnetic field and under a weak electromagnetic radiation with the frequency $\omega$. Due to the non-parabolic, linear energy dispersion, the particle responds not only at the frequency $\omega$ but generates a broad frequency spectrum around it. The linewidth of the cyclotron resonance turns out to be very broad even in a perfectly pure material which allows one to explain recent experimental data in graphene. It is concluded that the linear response theory does not work in graphene in finite magnetic fields.