Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous spectral weight in photoemission spectra of the hole doped
  Haldane chain Y2-xSrxBaNiO5   In this paper, we present photoemission experiments on the hole doped Haldane
chain compound $Y_{2-x}Sr_xBaNiO_5$. By using the photon energy dependence of
the photoemission cross section, we identified the symmetry of the first
ionisation states (d type). Hole doping in this system leads to a significant
increase in the spectral weight at the top of the valence band without any
change in the vicinity of the Fermi energy. This behavior, not observed in
other charge transfer oxides at low doping level, could result from the
inhomogeneous character of the doped system and from a Ni 3d-O 2p hybridization
enhancement due to the shortening of the relevant Ni-O distance in the
localized hole-doped regions.

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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
2
The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: q-bio