Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of spin diffusion in semi-insulating GaAs   We use optical transient-grating spectroscopy to measure spin diffusion of
optically oriented electrons in bulk, semi-insulating GaAs(100). Trapping and
recombination do not quickly deplete the photoexcited population. The spin
diffusion coefficient of 88 +/- 12 cm2/s is roughly constant at temperatures
from 15 K to 150 K, and the spin diffusion length is at least 450 nm. We show
that it is possible to use spin diffusion to estimate the electron diffusion
coefficient. Due to electron-electron interactions, the electron diffusion is
1.4 times larger than the spin diffusion.

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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: cs
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph