Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crossover from Kondo assisted suppression to co-tunneling enhancement of
  tunneling magnetoresistance via ferromagnetic nanodots in MgO tunnel barriers   Recently, it has been shown that magnetic tunnel junctions with thin MgO
tunnel barriers exhibit extraordinarily high tunneling magnetoresistance (TMR)
values at room temperature1, 2. However, the physics of spin dependent
tunneling through MgO barriers is only beginning to be unravelled. Using planar
magnetic tunnel junctions in which ultra-thin layers of magnetic metals are
deposited in the middle of a MgO tunnel barrier here we demonstrate that the
TMR is strongly modified when these layers are discontinuous and composed of
small pancake shaped nanodots. At low temperatures, in the Coulomb blockade
regime, for layers less than ~1 nm thick, the conductance of the junction is
increased at low bias consistent with Kondo assisted tunneling. In the same
regime we observe a suppression of the TMR. For slightly thicker layers, and
correspondingly larger nanodots, the TMR is enhanced at low bias, consistent
with co-tunneling.

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The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs