Gate-tunable plasmons in mixed-dimensional van der Waals heterostructures

Surface plasmons, collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light–matter interactions at the nanoscale. Plasmon dispersion of metallic structures depends sensitively on their dimensionality and has been intensively studied for fundamental physics as well as applied technologies. Here, we report possible evidence for gate-tunable hybrid plasmons from the dimensionally mixed coupling between one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene. In contrast to the carrier density-independent 1D Luttinger liquid plasmons in bare metallic carbon nanotubes, plasmon wavelengths in the 1D-2D heterostructure are modulated by 75% via electrostatic gating while retaining the high figures of merit of 1D plasmons. We propose a theoretical model to describe the electromagnetic interaction between plasmons in nanotubes and graphene, suggesting plasmon hybridization as a possible origin for the observed large plasmon modulation. The mixed-dimensional plasmonic heterostructures may enable diverse designs of tunable plasmonic nanodevices.

Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin

The excitation spectrum in the region of the intraband (Dirac plasmon) and interband ( π plasmon) plasmons in graphene/Pt-skin terminated Pt 3 Ni(111) is reproduced by using an ab-initio method and an empirical model. The results of both methods are compared with experimental data. We discover that metallic screening by the Pt layer converts the square-root dispersion of the Dirac plasmon into a linear acoustic-like plasmon dispersion. In the long-wavelength limit, the Pt d electron excitations completely quench the π plasmon in graphene at about 4.1 eV, that is replaced by a broad peak at about 6 eV. Owing to a rather large graphene/Pt-skin separation (≈3.3 Å), the graphene/Pt-skin hybridization becomes weak at larger wave vectors, so that the π plasmon is recovered with a dispersion as in a free-standing graphene.

Особенности распространения плазмонов в графеновом бислое в условиях поперечного электрического поля

Dispersion relation for plasma waves in graphene bilayer has been investigated. Influence of the bias voltage on the dispersion curve for plasmon in bigraphene has been studied within random phase approximation. The possibility of controlling of energy and group velocity for plasmon by changing of bias voltage has been shown. The dependence of plasmon energy on the bias voltage has been predicted to have the nonmonotonous character. Effect of the temperature on the plasmon dispersion has been analyzed.

Исследование плазменных колебаний в стеклообразных диэлектриках методом полного внешнего отражения рентгеновских лучей

Glass-like dielectrics are studied by methods of plasmon dispersion and asymmetry of the number of localized electrons in the zone of formation of the total external reflection of x-rays and the excitation of plasma vibrations. Defined by the internal mechanical stress and the associated polarization of the investigated dielectrics. The absence of internal mechanical stress in a single crystal of lithium fluoride was found out, and the observed polarization is caused by a large macroscopic dipole moment in this single crystal