Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic Orbital Currents and Polarization in Mott Insulators   The standard view is that at low energies Mott insulators exhibit only
magnetic properties while charge degrees of freedom are frozen out as the
electrons become localized by a strong Coulomb repulsion. We demonstrate that
this is in general not true: for certain spin textures {\it spontaneous
circular electric currents} or {\it nonuniform charge distribution} exist in
the ground state of Mott insulators. In addition, low-energy ``magnetic''
states contribute comparably to the dielectric and magnetic functions
$\epsilon_{ik}(\omega)$ and $\mu_{ik}(\omega)$ leading to interesting phenomena
such as rotation the electric field polarization and resonances which may be
common for both functions producing a negative refraction index in a window of
frequencies.

31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess