Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Seeing the orbital ordering in Iron-based superconductors with magnetic
  anisotropy   The orbital fluctuation of the conduction electrons in the Iron-based
superconductors is found to contribute significantly to the magnetic response
of the system. With the use of a realistic five-band model and group
theoretical analysis, we have determined the orbital magnetic susceptibility in
such a multi-orbital system. At $n=6.1$, the in-plane orbital magnetic
susceptibility is predicted to be about 10$\mu_{\mathrm{B}}^{2}/\mathrm{eV}$,
which is more than 2/3 of the observed total susceptibility around 200 K in 122
systems(of about 14$\mu_{\mathrm{B}}^{2}/\mathrm{eV}$ or
$4.5\times10^{-4}\mathrm{erg}/\mathrm{G}^{2}\mathrm{mol}_{\mathrm{AS}}$\cite{Klingeler}).
We find the in-plane orbital magnetic response is sensitive to the breaking of
the tetragonal symmetry in the orbital space. In particular, when the observed
band splitting(between the $3d_{xz}$ and the $3d_{yz}$-dominated band) is used
to estimate the strength of the symmetry breaking perturbation\cite{Shen}, a
4.5% modulation in the in-plane orbital magnetic susceptibility can be
produced, making the latter a useful probe of the orbital ordering in such a
multi-orbital system. As a by product, the theory also explains the large
anisotropy between the in-plane and the out-of-plane magnetic response observed
universally in susceptibility and NMR measurements.

12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph