Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Muon Spin Rotation Measurement of the Magnetic Field Penetration Depth
  in Ba(Fe0.93 Co0.07)2 As2 : Evidence for Multiple Superconducting Gaps   We have performed transverse field muon spin rotation measurements of single
crystals of Ba(Fe$_{0.93}$Co$_{0.07})_2$As$_2$ with the applied magnetic field
along the $\hat{c}$ direction. Fourier transforms of the measured spectra
reveal an anisotropic lineshape characteristic of an Abrikosov vortex lattice.
We have fit the $\mu$SRSR spectra to a microscopic model in terms of the
penetration depth $\lambda$ and the Ginzburg-Landau parameter $\kappa$.
  We find that as a function of temperature, the penetration depth varies more
rapidly than in standard weak coupled BCS theory. For this reason we first fit
the temperature dependence to a power law where the power varies from 1.6 to
2.2 as the field changes from 200G to 1000G. Due to the surprisingly strong
field dependence of the power and the superfluid density we proceeded to fit
the temperature dependence to a two gap model, where the size of the two gaps
is field independent. From this model, we obtained gaps of
$2\Delta_1=3.7k_BT_c$ and $2\Delta_2=1.6k_BT_c$, corresponding to roughly 6 meV
and 3 meV respectively.

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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: cs
30
The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph