Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: FeTe$_{0.55}$Se$_{0.45}$: a multiband superconductor in the clean and
  dirty limit   The detailed optical properties of the multiband iron-chalcogenide
superconductor FeTe$_{0.55}$Se$_{0.45}$ have been reexamined for a large number
of temperatures above and below the critical temperature $T_c=14$ K for light
polarized in the a-b planes. Instead of the simple Drude model that assumes a
single band, above $T_c$ the normal-state optical properties are best described
by the two-Drude model that considers two separate electronic subsystems; we
observe a weak response ($\omega_{p,D;1}\simeq 3000$ cm$^{-1}$) where the
scattering rate has a strong temperature dependence ($1/\tau_{D,1}\simeq 32$
cm$^{-1}$ for $T \gtrsim T_c$), and a strong response ($\omega_{p,D;2}\simeq
14\,500$ cm$^{-1}$) with a large scattering rate ($1/\tau_{D,2}\simeq 1720$
cm$^{-1}$) that is essentially temperature independent. The multiband nature of
this material precludes the use of the popular generalized-Drude approach
commonly applied to single-band materials, implying that any structure observed
in the frequency dependent scattering rate $1/\tau(\omega)$ is spurious and it
cannot be used as the foundation for optical inversion techniques to determine
an electron-boson spectral function $\alpha^2 F(\omega)$. Below $T_c$ the
optical conductivity is best described using two superconducting optical gaps
of $2\Delta_1\simeq 45$ and $2\Delta_2 \simeq 90$ cm$^{-1}$ applied to the
strong and weak responses, respectively. The scattering rates for these two
bands are vastly different at low temperature, placing this material
simultaneously in both clean and dirty limit. Interestingly, this material
falls on the universal scaling line initially observed for the cuprate
superconductors.

15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th