Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Role of covalent Fe-As bonding in the magnetic moment formation and
  exchange mechanisms in iron-pnictide superconductors   The electronic origin of the huge magnetostructural effect in layered Fe-As
compounds is elucidated using LiFeAs as a prototype. The crucial feature of
these materials is the strong covalent bonding between Fe and As, which tends
to suppress the exchange splitting. The bonding-antibonding splitting is very
sensitive to the distance between Fe and As nuclei. We argue that the fragile
interplay between bonding and magnetism is universal for this family of
compounds. The exchange interaction is analyzed in real space, along with its
correlation with covalency and doping. The range of interaction and itinerancy
increase as the Fe-As distance is decreased. Superexchange makes a large
antiferromagnetic contribution to the nearest-neighbor coupling, which develops
large anisotropy when the local moment is not too small. This anisotropy is
very sensitive to doping.

30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs