Extremely short optical pulse in a thin-film topological insulator with a hexagonal lattice

The propagation of an extremely short optical pulse in a thin-film topological insulator has been considered. The electrons are described by a low-temperature long-wavelength effective Hamiltonian, whereas the electromagnetic field is treated classically within the Maxwell??s equations. The dependence on the velocity and maximum amplitude of the extremely short pulse has been revealed.     

Propagation of extremely short optical pulses in impurity carbon nanotubes in dispersive and nonlinear media

Maxwell equations describing an extremely short pulse propagating in impurity carbon nanotubes placed in a dispersive nonmagnetic medium are analyzed with allowance for the nonlinearity of the medium. The dependences of the magnetic field intensity on the initial pulse amplitude and the parameters of the medium are revealed.     

Absolute negative conductivity in graphene with the Hubbard interaction in a magnetic field

The current-voltage and current-magnetic field characteristics for a graphene with the electron Hubbard interaction at low temperatures have been calculated in terms of the average electron method. The characteristics obtained have been analyzed as a function of the frequency of the external ac electric field and the magnetic field strength. The portion with an absolute negative conductivity has been revealed.     

Alternating field-induced phase transition in zigzag carbon nanotubes

We predict the possibility of spontaneous emergence of a constant electric field in carbon nanotubes if a high-frequency electric field is applied to them. The effect can be related to the nonequilibrium state of the electron subsystem of carbon nanotubes. The characteristics of the spontaneous field with respect to the parameters of the problem under consideration are revealed.     

Discrete solitons in the bigraphene with adsorbed atomic hydrogen

The propagation of discrete solitons in the bigraphene waveguides was calculated according to the Anderson model. An effective equation analogous to the classical sine-Gordon formula was obtained. The dependence of energy distribution between the waveguides of the graphene bilayers with adsorbed atomic hydrogen on the initial pulse width was studied.     

The effect of spin-orbit interaction on the dynamics of ultimately short pulses in graphene systems

The effect of the spin-orbit interaction of graphene electrons placed on a Ni (111) surface on the dynamics ultimately short pulses is considered. The dispersion law of electrons in graphene is calculated on the basis of the Rashba Hamiltonian. The dynamics of an ultimately short electromagnetic pulse considering the Rashba interaction and without it is under investigation.     

Curved graphene nanoribbons and tunneling current

The density of states and the electronic spectrum of long-wave electrons in a curved graphene nanoribbon is calculated on the basis of the Dirac equation in curved space-time. Using this density of states, we obtain the current-voltage characteristics of tunnel junctions of nanoribbons with metal and quantum dots. The dependence of the curved nanoribbon on the geometric parameters is found.     

Absolute negative conductivity in zig-zag carbon nanotubes in the presence of a magnetic field

The volt-ampere and gauss-ampere characteristics of zig-zag carbon nanotubes are calculated at low temperatures based on the average electron method. The characteristics obtained are analyzed as functions of the magnetic field strength. It is revealed that a constant electric field can arise spontaneously in carbon nanotubes upon application of an alternating high-frequency electric field. This effect can be due to the nonequilibrium electron subsystem of the carbon nanotubes.     

Ferroelectric phase transition in graphene with the Hubbard interaction

It has been revealed that, as an external dc electric field is applied to graphene with the Hubbard interaction between electrons, a spontaneous electric field perpendicular to the applied field can appear. This effect can be due to the nonequilibrium electron subsystem in graphene. The spontaneous field characteristics have been found as a function of the parameters of the problem.