Acoustoelectric current in graphene nanoribbon due to Landau damping.

We perform self-consistent analysis of the Boltzmann transport equation for momentum and energy in the hypersound regime i.e., [Formula: see text] ([Formula: see text] is the acoustic wavenumber and l is the mean free path). We investigate the Landau damping of acoustic phonons ([Formula: see text]) in graphene nanoribbons, which leads to acoustoelectric current generation. Under a non-quantized field with drift velocity, we observed an acoustic phonon energy quantization that depends on the energy gap, the width, and the sub-index of the material. An effect similar to Cerenkov emission was observed, where the electron absorbed the confined acoustic phonon energy, causing the generation of acoustoelectric current in the graphene nanoribbon. A qualitative analysis of the dependence of the absorption coefficient and the acoustoelectric current on the phonon frequency is in agreement with experimental reports. We observed a shift in the peaks when the energy gap and the drift velocity were varied. Most importantly, a transparency window appears when the absorption coefficient is zero, making graphene nanoribbons a potential candidate for use as an acoustic wave filter with applications in tunable gate-controlled quantum information devices and phonon spectrometers.

Theoretical study of electromagnetic transport in Lepidoptera Danaus plexippus wing scales.

This paper examines the electromagnetic energies developed in the scales of the Lepidoptera Danaus plexippus. The Green tensor method was used to calculate and simulate the energies at specific wavelengths. Scattering of electromagnetic waves within the scales was simulated at different wavelengths (λ) with the corresponding maximum energy occurred at λ = 0.45 µm. The study shows that the design of wing's cross-ribs maximizes the eigenmode of electromagnetic energy. This shows promising applications in bio-sensors of Solar light and likewise in waveguide for photonic transmission.