Papers by Keyword: Electron-Phonon Interactions

Abstract: We study the phonon-assisted Fano interference of the linear conductance spectrum by taking into account the interdot-phonon exchange in a T-shaped double quantum dot (QD), where a central QD is coupled to a side QD and two nonmagnetic or ferromagnetic electrodes. Unlike the usual Fano interference between different elastic channels,this new-type Fano interference is shown to arise from electron waves tunneling coherently through phonon-assisted bonding and antibonding states.

Abstract: Theoretical and practical principles of interaction of light with systems of metallic localized nanoparticles have been outlined and the importance of the electron-optical phonon resonance detuning effect was emphasized to design and develop nanotechnology devices. The demonstration of solar radiation interaction with surface-located gold nanoparticles on rutile was resulted in about 20 times enhancement in energy absorption. This gives possibility to improve different techniques such as energy conversion using optimally structured surfaces.

Abstract: In the second half of the twentieth century and in the first decade of the twenty first century, many new phenomena came to light in the fields of condensed matter and of materials properties’ at low temperatures. A few examples of these phenomena are: the plasticity and the behavior of dislocations in solid helium-4 (a quantum solid), “high” temperature superconductivity, occurrence of superfluid flow in solid helium (“supersolid”), and, Bose-Einstein condensation of cold atoms. In this presentation descriptions and some discussions are given on the role played in these studies by ultrasonic and other forms of mechanical spectroscopy.

Abstract: The temperature and particle size dependence of the holewidths for the 7F0 → 5D0 transition of Eu3+ ions in Eu2O3 are calculated and compared with experiment. The calculation is able to describe the effect of nanocrystal vibrational modes on the dephasing of the electronic states of probe ions. The nanocrystal was treated as an elastically isotropic sphere from which the acoustic phonon displacements and phonon spectrum were calculated. Then we applied this to the temperature and size dependencies of the electron-phonon interaction. Also the vibrational modes in nanocrystals are discussed.

Abstract: The calculation of the local density of electronic states of graphene with vacancies, using the method of Jacobi matrix, was performed. It was shown that for atoms in the sublattice with a vacancy the local density of electronic states conserves the Dirac singularity, similarly as in an ideal graphene. A quasi-Dirac singularity was observed also in the phonon spectra of graphite for the atom displacements in the direction perpendicular to layers. Changes of phonon spectra of graphite intercalated with various metals were analyzed. On the basis of our results and using the BCS theory and Eliashberg equation we proposed what dynamic properties an intercalated graphite system should show to obtain an increased Tc.

Abstract: The optical gain in the active region of quantum cascade laser in an external magnetic field is analyzed. When the magnetic field is applied in the direction perpendicular to the plane of the layers, electron dispersion is broken into series of discrete Landau levels. This additional confinement strongly modifies the lifetime of electrons in the upper state of the laser transition, which is controlled by electron-phonon scattering. Landau levels are magnetically tuneable and, depending on their configuration, phonon emission is either inhibited or resonantly enhanced. This translates into a strong modulation of the population inversion, and consequently of the optical gain by varying the magnetic field. Numerical results are presented for a structure previously considered by Smirnov et al. [Phys. Rev B 66 (2002) 125317] which is designed to emit radiation at λ~11.4µm, with the magnetic field varied in the range 10-60T. The effects of band nonparabolicity are taken into account in this model.