Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Possible two-gap superconductivity in NdFeAs(O,F) probed by
  point-contact Andreev-reflection spectroscopy   Systematic studies of the NdFeAsOF superconducting energy gap via the
point-contact Andreev-reflection (PCAR) spectroscopy are presented. The PCAR
conductance spectra show at low temperatures a pair of gap-like peaks at about
4 - 7 mV indicating the superconducting energy gap and in most cases also a
pair of humps at around 10 mV. Fits to the s-wave two-gap model of the PCAR
conductance allowed to determine two superconducting energy gaps in the system.
The energy-gap features however disappear already at T* = 15 to 20 K, much
below the particular Tc of the junction under study. At T* a zero-bias
conductance (ZBC) peak emerges, which at higher temperatures usually overwhelms
the spectrum with intensity significantly higher than the conductance signal at
lower temperatures. Possible causes of this unexpected temperature effect are
discussed. In some cases the conductance spectra show just a reduced
conductance around the zero-bias voltage, the effect persisting well above the
bulk transition temperature. This indicates a presence of the pseudogap in the
system.

26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs