Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mechanism for Magnetic Flux Generation in Grain Boundaries of YBCO   The spontaneously generated magnetic flux observed by Mannhart et. al. (1996)
in 45 degree grain boundaries in YBCO was explained by them in terms of a
d-wave superconducting order parameter and grain boundary faceting. This
article argues that twin boundaries which contact the grain boundary also play
an important role.

34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc