Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Upper Critical Fields up to 60T in Dirty Magnesium Diboride Thin Films   Upper critical fields of several magnesium diboride thin films were measured
up to 28 T at the Grenoble High Magnetic Field Laboratory (GHMFL) in Grenoble
and up to 60 T at the Laboratoire National des Champs Magnetiques Pulses
(LNCMP) in Toulouse. The samples were prepared both by pulsed laser deposition
(PLD) and hybrid physical chemical vapour deposition (HPCVD) technique; they
have critical temperatures between 29 and 39 K and normal state resistivities
between 5 and 250 &#956;ohmcm; one of them has been intentionally doped with
carbon. The measured critical fields were exceptionally high; we obtained the
record value of 52 T at 4.2 K in the parallel orientation. In contrast with the
BCS predictions, no saturation in Hc2 at low temperature was observed.
Furthermore, films with a wide range of resistivity values showed similar
critical fields, suggesting that in a two band system resistivity and Hc2 are
not trivially linked. The high Hc2 values seem to be related with the expanded
c-axis. The structure of one of the samples was carefully investigated with
X-ray diffraction at European Synchrotron Radiation Facility (ESRF) in
Grenoble.

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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: physics
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex