Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electrical generation of pure spin currents in a two-dimensional
  electron gas   Pure spin currents are measured in micron-wide channels of GaAs
two-dimensional electron gas (2DEG). Spins are injected and detected using
quantum point contacts, which become spin polarized at high magnetic field.
High sensitivity to the spin signal is achieved in a nonlocal measurement
geometry, which dramatically reduces spurious signals associated with charge
currents. Measured spin relaxation lengths range from 30 to 50 microns, much
longer than has been reported in GaAs 2DEG's. The technique developed here
provides a flexible tool for the study of spin polarization and spin dynamics
in mesoscopic structures defined in 2D semiconductor systems.

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The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th