arXiv subjects

A. V. Okotrub

Publications and source records attributed to A. V. Okotrub.

6 recordsLinked to original sources

arXiv2020

A memristive model for graphene emitters: hysteresis and self-crossing

Hysteresis exhibited by current-voltage characteristics during field-emission experiments is often considered undesirable in terms of practical applications. However, this is an appealing effect for the purposes of memristive devices. We developed a two-stage model to describe hysteretic characteristics, with a particular focus on the system which includes a cathode made of a single-layered graphene sheet on a substrate. In addition to hysteresis, the current-voltage curves display also an unusual self-crossing behavior. The presented memristive model can be used for quantitative descriptions of different hysteretic characteristics such as abrupt changes and self-crossings and for understanding (and modeling) the processes associated with field emission from plane graphene emitters.

cond-mat.mes-hall↗

arXiv2016

Memristive model of hysteretic field emission from carbon nanotube arrays

Some instances of electron field emitters are characterized by frequency-dependent hysteresis in their current-voltage characteristics. We argue that such emitters can be classified as memristive systems and introduce a general framework to describe their response. As a specific example of our approach, we consider field emission from a carbon nanotube array. Our experimental results demonstrate a low-field hysteresis, which is likely caused by an electrostatic alignment of some of the nanotubes in the applied field. We formulate a memristive model of such phenomenon whose results are in agreement with the experimental results.

cond-mat.mes-hall↗

arXiv2010

Fluorographene: Two Dimensional Counterpart of Teflon

We report a stoichiometric derivative of graphene with a fluorine atom attached to each carbon. Raman, optical, structural, micromechanical and transport studies show that the material is qualitatively different from the known graphene-based nonstoichiometric derivatives. Fluorographene is a high-quality insulator (resistivity >10^12 Ohm per square) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting Young's modulus of 100 N/m and sustaining strains of 15%. Fluorographene is inert and stable up to 400C even in air, similar to Teflon.

cond-mat.mtrl-sci↗

arXiv2006

Electron-electron interaction in carbon nanostructures

The electron-electron interaction in carbon nanostructures was studied. A new method which allows to determine the electron-electron interaction constant $λ_c$ from the analysis of quantum correction to the magnetic susceptibility and the magnetoresistance was developed. Three types of carbon materials: arc-produced multiwalled carbon nanotubes (arc-MWNTs), CVD-produced catalytic multiwalled carbon nanotubes (c-MWNTs) and pyrolytic carbon were used for investigation. We found that $λ_c$=0.2 for arc-MWNTs (before and after bromination treatment); $λ_c$ = 0.1 for pyrolytic graphite; $λ_c >$ 0 for c-MWNTs. We conclude that the curvature of graphene layers in carbon nanostructures leads to the increase of the electron-electron interaction constant $λ_c$.

cond-mat.mtrl-sci↗

arXiv2004

Anisotropy of x-ray scattering in aligned nanotube structures

Effects of orientational x-ray scattering have been experimentally examined in a film of vertically aligned multiwall carbon nanotubes (CNs). Additional contribution to the x-ray fluorescence intensity was revealed at angles close to the film normal. Theoretical considerations suggest the intensity enhancement to be caused by propagation of C K$_α$-radiation mainly along the channels of CNs.

physics.optics↗

arXiv2001

Electron-electron interaction in multiwall carbon nanotubes

Magnetic susceptibility $χ$ of pristine and brominated arc-produced sample of multiwall carbon nanotubes was measured from 4.2 to 400 K. An additional contribution $Δχ(T)$ to diamagnetic susceptibility $χ(T)$ of carbon nanotubes was found at T $<$ 50 K for both samples. It is shown that $Δχ(T)$ are dominated by quantum correction to $χ$ for interaction electrons (interaction effects-IE). The IE shows a crossover from two-dimensional to three-dimensional at $B$ = 5.5 T. The effective interaction between electrons for interior layers of nanotubes are repulsion and the electron-electron interaction $λ$$_c$ was estimated to be $λ_c\sim $ 0.26.

cond-mat.str-el↗