Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of Rb and Cs-doping on superconducting properties of MgB2 thin
  films   Our Rutherford backscattering spectrometry (RBS) study has found that
concentrations up to 7 atomic percent of Rb and Cs can be introduced to a depth
of ~700 A in MgB2 thin films by annealing in quartz ampoules containing
elemental alkali metals at <350 degree centigrade. No significant change in
transition temperature (Tc) was observed, in contrast to an earlier report of
very high Tc (>50 K) for similar experiments on MgB2 powders. The lack of a
significant change in Tc and intra-granular carrier scattering suggests that Rb
and Cs diffuse into the film, but do not enter the grains. Instead, the
observed changes in the electrical properties, including a significant drop in
Jc and an increase in delta rho (rho300-rho40), arise from a decrease in
inter-granular connectivity due to segregation of the heavy alkaline metals and
other impurities (i.e. C and O) introduced into the grain boundary regions
during the anneals.

8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int