Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Visualizing supercurrents in ferromagnetic Josephson junctions with
  various arrangements of 0 and \pi segments   Josephson junctions with ferromagnetic barrier can have positive or negative
critical current depending on the thickness $d_F$ of the ferromagnetic layer.
Accordingly, the Josephson phase in the ground state is equal to 0 (a
conventional or 0 junction) or to $\pi$ ($\pi$ junction). When 0 and $\pi$
segments are joined to form a "0-$\pi$ junction", spontaneous supercurrents
around the 0-$\pi$ boundary can appear. Here we report on the visualization of
supercurrents in superconductor-insulator-ferromagnet-superconductor (SIFS)
junctions by low-temperature scanning electron microscopy (LTSEM). We discuss
data for rectangular 0, $\pi$, 0-$\pi$, 0-$\pi$-0 and 20 \times 0-$\pi$
junctions, disk-shaped junctions where the 0-$\pi$ boundary forms a ring, and
an annular junction with two 0-$\pi$ boundaries. Within each 0 or $\pi$ segment
the critical current density is fairly homogeneous, as indicated both by
measurements of the magnetic field dependence of the critical current and by
LTSEM. The $\pi$ parts have critical current densities $j_c^\pi$ up to
$35\units{A/cm^2}$ at $T = 4.2\units{K}$, which is a record value for SIFS
junctions with a NiCu F-layer so far. We also demonstrate that SIFS technology
is capable to produce Josephson devices with a unique topology of the 0-$\pi$
boundary.

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The categories of this paper are: atom-ph
12
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: chem-ph
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
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The categories of this paper are: nlin
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: eess
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg