Pseudospin excitations in coaxial nanotubes

TL;DR

This paper investigates pseudospin excitations in coaxial nanotubes, analyzing how magnetic fields and Coulomb interactions influence resonance frequency, linewidth, and damping, revealing tunable collective oscillations in such nanostructures.

Contribution

It provides a theoretical analysis of pseudospin resonance in coaxial nanotubes, including the effects of magnetic fields and Coulomb interactions, with derived expressions for resonance frequency and linewidth.

Findings

Resonance frequency shifts depend on magnetic field and Coulomb interactions.

Linewidth of pseudospin excitations varies with magnetic field, showing peaks and damping suppression.

Large magnetic fields reduce the resonance shift due to Zeeman splitting.

Abstract

In a 2DEG confined to two coaxial tubes the `tube degree of freedom' can be described in terms of pseudospin-1/2 dynamics. The presence of tunneling between the two tubes leads to a collective oscillation known as pseudospin resonance. We employ perturbation theory to examine the dependence of the frequency of this mode with respect to a coaxial magnetic field for the case of small intertube distances. Coulomb interaction leads to a shift of the resonance frequency and to a finite lifetime of the pseudospin excitations. The presence of the coaxial magnetic field gives rise to pronounced peaks in the shift of the resonance frequency. For large magnetic fields this shift vanishes due to the effects of Zeeman splitting. Finally, an expression for the linewidth of the resonance is derived. Numerical analysis of this expression suggests that the linewidth strongly depends on the coaxial magnetic field, which leads to several peaks of the linewidth as well as regions where damping is almost completely suppressed.