Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Control of defect-mediated tunneling barrier heights in ultrathin MgO
  films   The impact of oxygen vacancies on local tunneling properties across
rf-sputtered MgO thin films was investigated by optical absorption spectroscopy
and conducting atomic force microscopy. Adding O$_2$ to the Ar plasma during
MgO growth alters the oxygen defect populations, leading to improved local
tunneling characteristics such as a lower density of current hotspots and a
lower tunnel current amplitude. We discuss a defect-based potential landscape
across ultrathin MgO barriers.

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The categories of this paper are: q-bio
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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: econ
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: hep-ex