17 research outputs found
Lifetime of metastable states in resonant tunneling structures
We investigate the transport of electrons through a double-barrier
resonant-tunneling structure in the regime where the current-voltage
characteristics exhibit bistability. In this regime one of the states is
metastable, and the system eventually switches from it to the stable state. We
show that the mean switching time grows exponentially as the voltage across the
device is tuned from the its boundary value into the bistable region. In
samples of small area we find that the logarithm of the lifetime is
proportional to the voltage (measured from its boundary value) to the 3/2
power, while in larger samples the logarithm of the lifetime is linearly
proportional to the voltage.Comment: REVTeX 4, 5 pages, 3 EPS-figure
Tunneling decay in a magnetic field
We provide a semiclassical theory of tunneling decay in a magnetic field and
a three-dimensional potential of a general form. Because of broken
time-reversal symmetry, the standard WKB technique has to be modified. The
decay rate is found from the analysis of the set of the particle Hamiltonian
trajectories in complex phase space and time. In a magnetic field, the
tunneling particle comes out from the barrier with a finite velocity and behind
the boundary of the classically allowed region. The exit location is obtained
by matching the decaying and outgoing WKB waves at a caustic in complex
configuration space. Different branches of the WKB wave function match on the
switching surface in real space, where the slope of the wave function sharply
changes. The theory is not limited to tunneling from potential wells which are
parabolic near the minimum. For parabolic wells, we provide a bounce-type
formulation in a magnetic field. The theory is applied to specific models which
are relevant to tunneling from correlated two-dimensional electron systems in a
magnetic field parallel to the electron layer.Comment: 16 pages, 11 figure
Enhancement of tunneling from a correlated 2D electron system by a many-electron Mossbauer-type recoil in a magnetic field
We consider the effect of electron correlations on tunneling from a 2D
electron layer in a magnetic field parallel to the layer. A tunneling electron
can exchange its momentum with other electrons, which leads to an exponential
increase of the tunneling rate compared to the single-electron approximation.
Explicit results are obtained for a Wigner crystal. They provide a qualitative
and quantitative explanation of the data on electrons on helium. We also
discuss tunneling in semiconductor heterostructures.Comment: published version, 4 pages, 2 figures, RevTeX 3.
Tunneling transverse to a magnetic field, and how it occurs in correlated 2D electron systems
We investigate tunneling decay in a magnetic field. Because of broken
time-reversal symmetry, the standard WKB technique does not apply. The decay
rate and the outcoming wave packet are found from the analysis of the set of
the particle Hamiltonian trajectories and its singularities in complex space.
The results are applied to tunneling from a strongly correlated 2D electron
system in a magnetic field parallel to the layer. We show in a simple model
that electron correlations exponentially strongly affect the tunneling rate.Comment: 4 pages, 3 figure
Self-consistent analysis of absorption and emission data forF A centres in alkali halides
Ratchet driven by quasimonochromatic noise.
The currents generated by noise-induced activation processes in a periodic potential are investigated analytically, by digital simulation and by performing analog experiments. The noise is taken to be quasimonochromatic and the potential to be a smoothed sawtooth. Two analytic approaches are studied. The first involves a perturbative expansion in inverse powers of the frequency characterizing quasimonochromatic noise and the second is a direct numerical integration of the deterministic differential equations obtained in the limit of weak noise. These results, together with the digital and analog experiments, show that the system does indeed give rise, in general, to a net transport of particles. All techniques also show that a current reversal exists for a particular value of the noise parameters