1,144 research outputs found
Appearance of Negative Differential Conductivity in Graphene Nanoribbons at High-Harmonics
We theoretically study current dynamics of graphene nanoribbons subject to
bias dc and ac driven fields. We showed that graphene nanoribbons exhibit
negative high-harmonic differential conductivity. Negative differential
conductivity appears when bias electric filed is in the neighborhood of applied
ac filed amplitude. We also observe both even and odd high-harmonic negative
differential conductivity at wave mixing of two commensurate frequencies. The
even harmonics are more pronounced than the odd harmonics. A possible use of
the present method for generating terahertz frequencies at even harmonics in
graphene is suggested.Comment: 6 pages, 3 figure
General Scattering Mechanism and Transport in Graphene
Using quasi-time dependent semi-classical transport theory in RTA, we
obtained coupled current equations in the presence of time varying field and
based on general scattering mechanism . We
find that close to the Dirac point, the characteristic exponent
corresponds to acoustic phonon scattering. long-range Coulomb
scattering mechanism. is short-range delta potential scattering in
which the conductivity is constant of temperature. The case is
ballistic limit. In the low energy dynamics of Dirac electrons in graphene, the
effect of the time-dependent electric field is to alter just the electron
charge by making electronic conductivity
non-linear. The effect of magnetic filed is also considered.Comment: 8 pages, 3 figure
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