Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Agreement between local and global measurements of the London
  penetration depth   Recent measurements of the superconducting penetration depth in Ba(Fe_1-x
Co_x)2As2 appeared to disagree on the magnitude and curvature of
{\Delta}{\lambda}_{ab}(T), even near optimal doping. These measurements were
carried out on different samples grown by different groups. To understand the
discrepancy, we use scanning SQUID susceptometry and a tunnel diode resonator
to measure the penetration depth in a single sample. The penetration depth
observed by the two techniques is identical with no adjustments. We conclude
that any discrepancies arise from differences between samples, either in growth
or crystal preparation.

27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci