Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Power-law dependence of the optical conductivity observed in the quantum
  spin-liquid compound \kappa-(BEDT-TTF)2Cu2(CN)3   The Mott-insulator \kappa-(BEDT-TTF)_2Cu_2(CN)_3 is the prime candidate of a
quantum spin liquid with puzzling magnetic properties. Our THz and infrared
investigations reveal that also the charge dynamics does not follow the
expectations for a Mott insulator. The frequency-dependent conductivity
exhibits a power-law behavior $\sigma_1(\omega)\propto \omega^n$ that grows
stronger as the temperature decreases and extends all the way through the
far-infrared. With $n\approx 0.8$ to 1.5 we obtain a significantly smaller
exponent than predicted by Ng and Lee [Phys. Rev. Lett. {\bf 99}, 156402
(2007)]. We suggest fluctuations becomes important in the spin-liquid state and
couple to the electrodynamic properties differently compared to the
antiferromagnetic Mott insulator \kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl. We discuss
the various possibilities of how charge fluctuations are influenced by the
presence or absence of magnetic order.

22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
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The categories of this paper are: eess
3
The categories of this paper are: physics