Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reentrant superconductivity in YBa$_2$Cu$_3$O$_{7-d}$ microstructured
  particles   A reentrant superconducting effect was observed in YBCO particles as a
consequence of their size and microstructure. It rises from the coexistence
between bulk superconductivity and surface ferromagnetism, where the enhanced
magneto-electric coupling induced by broken spatial-inversion symmetry in
layers near structural defects plays a very important role on surface
ferromagnetism. The study assumes grain boundaries inside the particles act as
additional surface regions that enhance the ferromagnetic properties. Magnetic
and superconducting properties as a function of particle size were studied.
Particularly, the 385 nm particles which were the ones that exhibited the
reentrant superconducting effect. The Ginzburg-Landau parameter and the
critical temperatures are $k \sim 1.29$, T$_{c1}$ = 92 $\pm$ 5 K, and T$_{c2}$
= 10 $\pm$ 3 K.

22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg