7,290 research outputs found
Charge ordering and interlayer phase coherence in quantum Hall superlattices
The possibility of the existence of states with a spontaneous interlayer
phase coherence in multilayer electron systems in a high perpendicular to the
layers magnetic field is investigated. It is shown that phase coherence can be
established in such systems only within individual pairs of adjacent layers,
while such coherence does not exist between layers of different pairs. The
conditions for stability of the state with interlayer phase coherence against
transition to a charge-ordered state are determined. It is shown that in the
system with the number of layers N\leq 10 these conditions are satisfied at any
value of the interlayer distance d. For N>10 there are two intervals of
stability: at sufficiently large and at sufficiently small d. For N\to \infty
the stability interval in the region of small d vanishesComment: 10 page
Relaxation of superflow in a network: an application to the dislocation model of supersolidity of helium crystals
We have considered the dislocation network model for the supersolid state in
He-4 crystals. In difference with uniform 2D and 3D systems, the temperature of
superfluid transition T_c in the network is much smaller than the degeneracy
temperature T_d. It is shown that a crossover into a quasi superfluid state
occurs in the temperature interval between T_c and T_d. Below the crossover
temperature the time of decay of the flow increases exponentially under
decrease of the temperature. The crossover has a continuous character and the
crossover temperature does not depend on the density of dislocations.Comment: Corrected typo
Impurity induced bound states and proximity effect in a bilayer exciton condensate
The effect of impurities which induce local interlayer tunneling in bilayer
exciton condensates is discussed. We show that a localized single fermion bound
state emerges inside the gap for any strength of impurity scattering and
calculate the dependence of the impurity state energy and wave function on the
potential strength. We show that such an impurity induced single fermion state
enhances the interlayer coherence around it, and is similar to the
superconducting proximity effect. As a direct consequence of these single
impurity states, we predict that a finite concentration of such impurities will
increase the critical temperature for exciton condensation.Comment: 4 pages, 2 figure
Disruption of the three-body gravitational systems: Lifetime statistics
We investigate statistics of the decay process in the equal-mass three-body
problem with randomized initial conditions. Contrary to earlier expectations of
similarity with "radioactive decay", the lifetime distributions obtained in our
numerical experiments turn out to be heavy-tailed, i.e. the tails are not
exponential, but algebraic. The computed power-law index for the differential
distribution is within the narrow range, approximately from -1.7 to -1.4,
depending on the virial coefficient. Possible applications of our results to
studies of the dynamics of triple stars known to be at the edge of disruption
are considered.Comment: 13 pages, 2 tables, 3 figure
Grouping Method Of Image Fragments Of Adjacent Dislocation Etch Pits Of The Semiconductor Wafer
An increase in production volumes of gallium arsenide semiconductor devices determines the need for better control of dislocations of semiconductor wafer.The grouping method of image fragments of adjacent dislocation etch pits of the semiconductor wafer is proposed in the article. Adjacent fragments will be allocated in the pre-binarized image of wafer surface, which contains adjacent fragments of etch pits of dislocation loops after treatment by the described method. Improved methods for determining the loop line width determines the edge line width of etch pits of suspected dislocations, given the variability of their display in the binarized image. The current loop line width is compared to the reference line width of the dislocation loop.The grouping method of image fragments of adjacent dislocation etch pits of the semiconductor wafer defines recovery of loop lines branching, takes into account various options of line adjacency and determines the direction of further recovery of loop line of dislocation etch pits. A step by step description of the method is given
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