Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field-dependent diamagnetic transition in magnetic superconductor
  $Sm_{1.85} Ce_{0.15} Cu O_{4-y}$   The magnetic penetration depth of single crystal
$\rm{Sm_{1.85}Ce_{0.15}CuO_{4-y}}$ was measured down to 0.4 K in dc fields up
to 7 kOe. For insulating $\rm{Sm_2CuO_4}$, Sm$^{3+}$ spins order at the
N\'{e}el temperature, $T_N = 6$ K, independent of the applied field.
Superconducting $\rm{Sm_{1.85}Ce_{0.15}CuO_{4-y}}$ ($T_c \approx 23$ K) shows a
sharp increase in diamagnetic screening below $T^{\ast}(H)$ which varied from
4.0 K ($H = 0$) to 0.5 K ($H =$ 7 kOe) for a field along the c-axis. If the
field was aligned parallel to the conducting planes, $T^{\ast}$ remained
unchanged. The unusual field dependence of $T^{\ast}$ indicates a spin freezing
transition that dramatically increases the superfluid density.

20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
12
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: plasm-ph
15
The categories of this paper are: nucl-ex