227,768 research outputs found
Radiation-induced magnetoresistance oscillation in a two-dimensional electron gas in Faraday geometry
Microwave-radiation induced giant magnetoresistance oscillations recently
discovered in high-mobility two-dimensional electron systems in a magnetic
field, are analyzed theoretically. Multiphoton-assisted impurity scatterings
are shown to be the primary origin of the oscillation. Based on a model which
considers the interaction of electrons with the electromagnetic fields in
Faraday geometry, we are able not only to reproduce the correct period, phase
and the negative resistivity of the main oscillation, but also to obtain
secondary peaks and additional maxima and minima in the resistivity curve, some
of which were already observed in the experiments.Comment: 4 pages, 1 figure, revised version to be published in Phys. Rev. Let
Fate of the Peak Effect in a Type-II Superconductor: Multicriticality in the Bragg-Glass Transition
We have used small-angle-neutron-scattering (SANS) and ac magnetic
susceptibility to investigate the global magnetic field H vs temperature T
phase diagram of a single crystal Nb in which a first-order transition of
Bragg-glass melting (disordering), a peak effect, and surface superconductivity
are all observable. It was found that the disappearance of the peak effect is
directly related to a multicritical behavior in the Bragg-glass transition.
Four characteristic phase boundary lines have been identified on the H-T plane:
a first-order line at high fields, a mean-field-like continuous transition line
at low fields, and two continuous transition line associated with the onset of
surface and bulk superconductivity. All four lines are found to meet at a
multicritical point.Comment: 4 figure
Isotropic and Anisotropic Lattice Spacing Corrections for I=2 pi-pi Scattering from Effective Field Theory
The calculation of the finite lattice spacing corrections for I=2 pi-pi
scattering is carried out for isotropic and anisotropic Wilson lattice actions.
Pion masses and decay constants are also determined in this context. These
results correct the phase shift calculated from the lattice, which is connected
to the scattering length and effective range in this low energy scattering
process. When in terms of the lattice-physical parameters for either Wilson
action, these lattice spacing effects first appear at the next-to-leading order
counter-terms.Comment: 15 pages, additional discussion of pion decay constant, version
published in PR
A cell death assay in barley and wheat protoplasts for identification and validation of matching pathogen AVR effector and plant NLR immune receptors
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