In work \cite{Kukhtaruk_UJP}, the studies of the interaction between a remote
nanoparticle and a drifting 2DEG at relatively low frequencies, i.e. when the
application of the “low-frequency” drift-diffusion approximation is valid, were started. In this work, we
present the results of our researches of THz-frequency properties of hybrid
systems in the “high-frequency” approximation for the electron motion in a 2DEG. We revealed
collective oscillations of interacting nanoparticles and the 2DEG.
In particular, we determined the frequencies of collective
oscillations and their extra damping stemming from the interaction
between the nanoparticle and plasmons. The damping character is
similar to that of Landau damping. This system was demonstrated to
become unstable under definite nonequilibrium conditions, i.e. there
emerges an increase of collective oscillations in time induced by an
electric current. The nanoparticle destroys the translational
symmetry, and the system becomes non-uniform, which promotes the
appearance of an instability, similarly to what takes place in
non-uniform or spatially confined
plasma \cite{f-length-1}.
The structure of the paper is as follows. In Section 2, the model of
a hybrid system is discussed, and the basic equations are
substantiated. In Section 3, the exact solutions of the equations
are obtained, and their general properties are examined. In
Section 4, the main attention is given to the stability/instability
of a hybrid system under the condition of two-dimensional electron
drift, the numerical results are presented, and the specific
examples of nanoparticles and heterostructures with two-dimensional
electrons are considered. The features of coordinated space-time
charge waves are dealt in Section 5. The properties of the NP dipole
moment, plasmon field, and emission by the hybrid system are studied
in Section 6. Conclusions are presented in Section 7.