Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Giant fluctuations of superconducting order parameter in
  Ferromagnet/superconductor single electron transistors   Spin dependent transport in a ferromagnet/superconductor/ferromagnet single
electron transistor is studied theoretically with spin accumulation, spin
relaxation, gap suppression, and charging effects taken into account. A strong
dependence of the gap on the magnetic state of the outer electrodes is found,
which gives rise to a negative magneto-resistance of up to 100 %. We predict
that fluctuations of the spin accumulation due to tunneling of quasi-particles
can play such an important role as to cause the island to fluctuate between the
superconducting

31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio