569,426 research outputs found
Interface effects in d-wave superconductor-ferromagnet junctions
Measurements of the differential conductance spectra of YBa2Cu3O7-SrRuO3 and
YBa2Cu3O7-La0.67Ca_0.33MnO3 ramp-type junctions along the node and anti-node
directions are reported. The results are consistent with a crossed Andreev
reflection effect only in YBa2Cu3O7-SrRuO3 junctions where the domain wall
width of SrRuO3 is comparable with the coherence length of YBa2Cu3O7. No such
effect was observed in the YBa2Cu3O7-La0.67Ca0.33MnO3 junctions, which is in
line with the much larger (x10) domain wall width of La0.67Ca0.33MnO3. We also
show that crossed Andreev exists only in the anti-node direction. Furthermore,
we find evidence that crossed Andreev in YBa2Cu3O7 junctions is not sensitive
to nm-scale interface defects, suggesting that the length scale of the crossed
Andreev effect is larger than the coherence length, but still smaller than the
La0.67Ca0.33MnO3's domain wall width.Comment: 5 pages, 6 figure
Growing network with j-redirection
A model for growing information networks is introduced where nodes receive
new links through j-redirection, i.e. the probability for a node to receive a
link depends on the number of paths of length j arriving at this node. In
detail, when a new node enters the network, it either connects to a randomly
selected node, or to the j -ancestor of this selected node. The j -ancestor is
found by following j links from the randomly selected node. The system is shown
to undergo a transition to a phase where condensates develop. We also find
analytical predictions for the height statistics and show numerically the
non-trivial behaviour of the degree distribution.Comment: 7 page
Interconnection network with a shared whiteboard: Impact of (a)synchronicity on computing power
In this work we study the computational power of graph-based models of
distributed computing in which each node additionally has access to a global
whiteboard. A node can read the contents of the whiteboard and, when activated,
can write one message of O(log n) bits on it. When the protocol terminates,
each node computes the output based on the final contents of the whiteboard. We
consider several scheduling schemes for nodes, providing a strict ordering of
their power in terms of the problems which can be solved with exactly one
activation per node. The problems used to separate the models are related to
Maximal Independent Set, detection of cycles of length 4, and BFS spanning tree
constructions
Minimum Distance Distribution of Irregular Generalized LDPC Code Ensembles
In this paper, the minimum distance distribution of irregular generalized
LDPC (GLDPC) code ensembles is investigated. Two classes of GLDPC code
ensembles are analyzed; in one case, the Tanner graph is regular from the
variable node perspective, and in the other case the Tanner graph is completely
unstructured and irregular. In particular, for the former ensemble class we
determine exactly which ensembles have minimum distance growing linearly with
the block length with probability approaching unity with increasing block
length. This work extends previous results concerning LDPC and regular GLDPC
codes to the case where a hybrid mixture of check node types is used.Comment: 5 pages, 1 figure. Submitted to the IEEE International Symposium on
Information Theory (ISIT) 201
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