Controlling magneto-absorption spectra of a graphene ribbon by a modulated electric field

This study shows that a spatially modulated sinusoidal electric field can significantly tune the magneto-absorption spectra of a graphene ribbon. The pattern of absorption spectra evolves with the amplitude of electric potential (V₀). When V₀ is weaker than the state energy of the first Landau level, E₁, the modulated electric field not only changes the peak intensity and peak position of the absorption lines, but also generates new peaks. These additional peaks follow the unusual optical selection rule. When V₀ is stronger than E₁, the intensity of original peaks, induced by the uniform magnetic field, shrinks, and an anomalous lowest peak appears. Most importantly, the energy position of the first peak strongly depends on both the amplitude of the electric potential and the strength of the magnetic field. These characteristics can be used to modulate the threshold frequency of the magneto-absorption spectra.