Impact of the energy dispersion anisotropy on the plasmonic structure in a two-dimensional electron system

The effect of the band structure anisotropy (triangular, square, and hexagonal wrapping) on the electronic collective excitations (plasmons) in a two-dimensional electron gas (2DEG) is studied in the framework of the random-phase approximation. We show that the dynamical dielectric response in these systems strongly depends on the direction of the in-plane momentum transfer q. The effect is so pronounced that it results in a different number of electronic collective excitations in some q regions, both with similar to root q- and similar to q-Like energy dispersions. This finding is in striking contrast to the conventional 2DEG case with isotropic energy band dispersion where only a single plasmon with similar to root q dispersion can exist. Our prediction of acoustic modes (with the similar to q dispersion) in a one-energy-band electron system expands the previous knowledge that such kind of plasmon can be realized only in two-component systems.

Automated summary

This study investigates the effect of band structure anisotropy on the electronic collective excitations in a two-dimensional electron gas. The researchers find that the dynamical dielectric response strongly depends on the direction of in-plane momentum transfer, resulting in different numbers of excitations with similar to root q and similar to q energy dispersions. This finding is in contrast to the conventional case of isotropic band dispersion where only a single plasmon can exist with similar to root q dispersion.