Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hole core in superconductors and the origin of the Spin Meissner effect   It is proposed that superconductors possess a hidden `hole core' buried deep
in the Fermi sea. The proposed hole core is a small region of the Brillouin
zone (usually at the center of the zone) where the lowest energy states in the
normal state reside. We propose that in the superconducting state these energy
states become {\it singly occupied} with electrons of a definite spin helicity.
In other words, that holes of a definite spin helicity condense from the top to
the bottom of the band in the transition to superconductivity, and electrons of
that spin helicity `float' on top of the hole core, thus becoming highly
mobile. The hole core has radius $q_0=1/2\lambda_L$, with $\lambda_L$ the
London penetration depth, and the electrons expelled from the hole core give an
excess negative charge density within a London penetration depth of the real
space surface of the superconductor. The hole core explains the development of
a spin current in the transition to superconductivity (Spin Meissner effect)
and the associated negative charge expulsion from the interior of metals in the
transition to superconductivity, effects we have proposed in earlier work to
exist in all superconductors and to be at the root of the Meissner effect.

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The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
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The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio