Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High Pressure Studies on Fe-Pnictide Superconductors   A review of high-pressure studies on Fe-pnictide superconductors is given.
The pressure effects on the magnetic and superconducting transitions are
discussed for different classes of doped and undoped FeAs-compounds, ROFeAs (R
= rare earth), AeFe2As2 (Ae = Ca, Sr, Ba), and AFeAs (A = Li, Na). Pressure
tends to decrease the magnetic transition temperature in the undoped or only
slightly doped compounds. The superconducting Tc increases with pressure for
underdoped FeAs-pnictides, remains approximately constant for optimal doping,
and decreases linearly in the overdoped range. The undoped LaOFeAs and AeFe2As2
become superconducting under pressure although nonhydrostatic pressure
conditions seem to play a role in CaFe2As2. The superconductivity in the
(undoped) AFeAs is explained as a chemical pressure effect due to the volume
contraction caused by the small ionic size of the A-elements. The binary FeSe
shows the largest pressure coefficient of Tc in the Se-deficient
superconducting phase.

33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
3
The categories of this paper are: physics
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con