Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative magnetoresistance in viscous flow of two-dimensional electrons   At low temperatures, in very clean two-dimensional (2D) samples the electron
mean free path for collisions with static defects and phonons becomes greater
than the sample width. Under this condition, the electron transport occurs by
formation of a viscous flow of an electron fluid. We study the viscous flow of
2D electrons in a magnetic field perpendicular to the 2D layer. We calculate
the viscosity coefficients as the functions of magnetic field and temperature.
The off-diagonal viscosity coefficient determines the dispersion of the 2D
hydrodynamic waves. The decrease of the diagonal viscosity in magnetic field
leads to negative magnetoresistance which is temperature- and size dependent.
Our analysis demonstrates that the viscous mechanism is responsible for the
giant negative magnetoresistance recently observed in the ultra-high-mobility
GaAs quantum wells. We conclude that 2D electrons in that structures in
moderate magnetic fields should be treated as a viscous fluid.

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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: acc-phys