arXiv subjects

Slava V. Rotkin

Publications and source records attributed to Slava V. Rotkin.

25 records · Page 2Linked to original sources

arXiv2004

Possibility of a Metallic Field-Effect Transistor

We develop theoretical arguments that demonstrate the possibility of metallic field-effect transistors (METFET's) in one-dimensional systems and particularly in armchair carbon nanotubes. A very inhomogeneous electric field, such as the field of a tunnelling tip, can penetrate the relatively weakly screened nanotubes and open an energy gap. As a consequence, an energy barrier forms that impedes electron flow and thus permits transistor action. This type of metallic field effect is advantageous because of the high conductance of the metallic tubes in the ON--state.

cond-mat.mtrl-sci↗

arXiv2003

Breaking of Nanotube Symmetry by Substrate Polarization

Substrate and nanotube polarization are shown to change qualitatively a nanotube bandstructure. The effect is studied in a linear approximation in an external potential which causes the changes. A work function difference between the nanotube and gold surface is estimated to be large enough to break the band symmetry and lift a degeneracy of a lowest but one subband of a metallic nanotube. This subband splitting for [10,10] nanotube is about 50 meV in absence of other external potential.

cond-mat.mtrl-sci↗

arXiv2002

Electronic response and bandstructure modulation of carbon nanotubes in a transverse electrical field

The electronic properties of carbon nanotubes in a uniform transverse field are investigated within a single orbital tight-binding model. For doped nanotubes, the dielectric function is found to depend not only on symmetry of the tube, but also on radius and Fermi level position. Bandgap opening/closing is predicted for zigzag tubes, while it is found that armchair tubes always remain metallic, which is explained by the symmetry in their configuration. The bandstructures for both types are considerably modified when the field strength is large enough to mix neighboring subbands.

cond-mat.mtrl-sci↗

arXiv2001

On surface energy of graphene and carbon nanoclusters

Theoretical study of graphite (graphene) edge is done. The most stable edge orientation is calculated to be a zigzag [110] edge. Possible applications of the result to the formation of different graphitic structures are discussed.

cond-mat.mtrl-sci↗

arXiv2000

Rolling up of graphite sheet: Energetics of shell formation

The energetics of transformation of a planar fragment of a graphite monolayer into a spherical cluster is studied. The path considered is that a flat cluster rolls up into a segment of a spherical shell. The energy landscape of the process is presented. A simple model, formerly invented for calculating the carbon nanocluster formation energy, is used to evaluate the energies of intermediate states. Although the spherical-shell closed cluster has the lowest energy, curving of a plane fragment into a segment has an energy barrier. The barrier height goes to zero for clusters with the number of atoms greater than some $N_{\rm th}$, for which the cluster size is found analytically.

cond-mat.mtrl-sci↗

arXiv2000

On depolarisation level shift in spherical QD

A giant level shift, resulted from the interaction of an electron in a spherical quantum dot with zero--point oscillations of confined modes of the electric field, is divulged. The energy correction depends on the dot radius. This size scaling of the depolarisation effect is computed semiclassically. A change of the optical properties of the matrix surrounding the dot provides a method to study the shift experimentally.

cond-mat.mtrl-sci↗

arXiv2000

Depolarisation of spherical-membrane quantum well: Gap renormalisation for closed-shell fullerenes

An anomalous large level shift is newly found to correct the one-electron spectrum of a closed-shell carbon nanocluster, for example, the spectrum which was described within the model of a thin quantum well rolled into a sphere. As a result of the interaction with zero-point oscillations of the confined modes of the electric field, the one-electron energy levels heighten. The depolarization depends on the electron momentum, why it does not shift the rotational spectrum as a whole. Surprisingly the shift in a spherical closed-shell cluster of an arbitrary size is described by an universal law. The non-equidistant shift of the levels results in an increase of an one-electron gap by 1.4 times.

cond-mat.mtrl-sci↗