Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical properties of magnetically doped ultra-thin topological
  insulator slabs   Starting from a three dimensional Hamiltonian, we study the optical
properties of ultra-thin topological insulator slabs for which the coupling
between Dirac fermions on opposite surfaces results in two degenerated gapped
hyperbolic bands. The gap is a threshold for the optical absorption and
translates in a peak in the imaginary part of the optical conductivity. An
exchange field applied perpendicular to the slab splits the degenerated
hyperbolic bands and a double step structure come out in the optical
absorption, whereas a double peak structure appears in the imaginary part of
the longitudinal optical conductivity. The exchange field breaks time-reversal
symmetry and for exchange fields larger than the surfaces coupling gap, the
zero frequency Hall conductivity is quantized to $e^2/h$. This result implies
large values of the Kerr and Faraday rotation angles. In ultra-thin slabs, the
absence of light multiple scattering and bulk conductivity, makes the Kerr and
Faradays angles to remain rather large in a wide range of frequencies.

28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an