Plasmons in topological insulator cylindrical nanowires

Abstract

We present a theoretical analysis of Dirac magneto-plasmons in topological insulator nanowires. We discuss a cylindrical geometry where Berry phase effects induce the opening of a gap at the neutrality point. By taking into account surface electron wave functions introduced in previous papers and within the random phase approximation, we provide an analytical form of the dynamic structure factor. Dispersions and spectral weights of Dirac plasmons are studied with varying the radius of the cylinder, the surface doping, and the strength of an external magnetic field. We show that, at zero surface doping, inter-band damped plasmon-like excitations form at the surface and survive at low electron surface dopings (∼ 10 10 cm −2 ). Then, we point out that the plasmon excitations are sensitive to the Berry phase gap closure when an external magnetic field close to half quantum flux is introduced. Indeed, a well-defined magneto-plasmon peak is observed at lower energies upon the application of the magnetic field. Finally, the increase of the surface doping induces a crossover from damped inter-band to sharp intra-band magneto-plasmons which, as expected for large radii and dopings (∼ 10 12 cm −2 ), approach the proper limit of a two-dimensional surface.

Ballistic transport through quantum point contacts of multi-orbital oxides

“…Moreover, we point out that, in the left panel of Fig. 2, the first three xy-like sub-bands show a clear double minimum close to k = 0, an effect that can be typically ascribed to the Rashba coupling in Rashba nanowires [29][30][31][32][33][34]. However, for the next xy-like sub-bands, the double-mininum gets reduced with increasing energy.…”

Photonics with Gallium Nitride Nanowires

“…The findings pointed out that the number of nanowires affects the coupling and that the flux density increases with the increase in the number of nanowires [33]. In order to explore the relation between the changes in the flux density and number of nanowires we plotted the data as shown in Figure 7.…”

Surface plasmons in anisotropic 3D gapped topological insulators

“…Metallic materials support plasmons which are collective oscillations of the free electrons against the positively charged background. Intrinsic plasmons in TIs have been extensively investigated, of which the dispersion relations can basically be found by calculating the electron energy loss spectrum [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. Apart from these intrinsic plasmons, metallic materials also have surface plasmons.…”