2,494 research outputs found
Transport equation for 2D electron liquid under microwave radiation plus magnetic field and the Zero Resistance State
A general transport equation for the center of mass motion is constructed to
study transports of electronic system under uniform magnetic field and
microwave radiation. The equation is applied to study 2D electron system in the
limit of weak disorder where negative resistance instability is observed when
the radiation field is strong enough. A solution of the transport equation with
spontaneous AC current is proposed to explain the experimentally observed
Radiation-Induced Zero Resistance State.Comment: 9 pages, 1 figur
Enhanced visibility of graphene: effect of one-dimensional photonic crystal
We investigate theoretically the light reflectance of a graphene layer
prepared on the top of one-dimensional Si/SiO2 photonic crystal (1DPC). It is
shown that the visibility of the graphene layers is enhanced greatly when 1DPC
is added, and the visibility can be tuned by changing the incident angle and
light wavelengths. This phenomenon is caused by the absorption of the graphene
layer and the enhanced reflectance of the 1DPC.Comment: 4 pages, 4 figures. published, ApplPhysLett_91_18190
Hadronic origin of prompt high-energy emission of gamma-ray bursts revisited: in the case of a limited maximum proton energy
The high-energy (> 100MeV) emission observed by Fermi-LAT during the prompt
phase of some luminous gamma-ray bursts (GRBs) could arise from the cascade
induced by interactions between accelerated protons and the radiation field of
GRBs. The photomeson process, which is usually suggested to operate in such a
hadronic explanation, requires a rather high proton energy (> 10^17eV) for an
efficient interaction. However, whether GRBs can accelerate protons to such a
high energy is far from guaranteed, although they have been suggested as the
candidate source for ultrahigh-energy cosmic rays. In this work, we revisit the
hadronic model for the prompt high-energy emission of GRBs with a smaller
maximum proton energy than the usually adopted value estimated from the Bohm
condition. In this case, the Bethe-Heitler pair production process becomes
comparably important or even dominates over the photomeson process. We show
that with a relatively low maximum proton energy with a Lorentz factor of 10^5
in the comoving frame, the cascade emission can still reproduce various types
of high-energy spectrum of GRBs. For most GRBs without high-energy emission
detected, the maximum proton energy could be even lower and relax the
constraints on the parameters of GRB jet resulting from the fact of
non-detection of GRB neutrinos by IceCube.Comment: 36 pages, 13 figures, accepted for publication in Ap
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