Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement and analysis of the Hall effect of A-Fe$_2$As$_2$ single
  crystals with A = Ba, Ca or Sr   We report measurements of the Hall coefficient $R_H$ for single crystals of
AFe$_2$As$_2$ with $A = Ba, Ca$ or $Sr$ which are the anti-ferromagnetic parent
compounds of some high temperature pnictide superconductors. We show that $R_H$
of Sr-122 is consistent with high field quantum oscillation data. Our $R_H(T)$
data can also be used to estimate values of the spin density wave gap, giving
$\Delta_{SDW}(0) = 710\pm 70$ K for Sr-122 and $435\pm 20$ K for Ba-122.

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The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
1
The categories of this paper are: cs
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th