Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropic Electrical Spin Injection in Ferromagnetic Semiconductor
  Heterostructures   A fourteen-fold anisotropy in the spin transport efficiency parallel and
perpendicular to the charge transport is observed in a vertically-biased
(Ga,Mn)As-based spin-polarized light emitting diode. The spin polarization is
determined by measuring the polarization of electroluminescence from an
(In,Ga)As quantum well placed a distance d (20 to 420 nm) below the p-type
ferromagnetic (Ga,Mn)As contact. In addition, a monotonic increase from 0.5 to
7% in the polarization is measured as d decreases for collection parallel to
the growth direction, while the in-plane polarization from the perpendicular
direction (~0.5%) remains unchanged.

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The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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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: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int