Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Room temperature study of a strain-induced electronic superstructure on
  a magnetite (111) surface   A magnetite (Fe3O4) single crystal (111) surface has been studied at various
oxygen-iron surface stoichiometries. The stoichiometry was modified by
controlling the in-situ sample anneal conditions. We have found the conditions
that lead to the formation of an oxygen-rich surface that forms a
quasi-hexagonal superstructure with a 42A periodicity. The superstructure is
highly regular and was observed by both LEED and STM. The superstructure
consists of three regions, two of which have identical atomic scale structures
with a periodicity of 2.8A, and a third having a periodicity that is about 10%
larger (3.1A). The subtle difference in the atomic periodicities between the
three areas results from the modulation of intrinsic strain developed along the
surface. The superstructure results from electronic effects rather than being a
mosaic of different iron oxide terminations. The onset of the superstructure is
sensitive to the surface stoichiometry. From our results we could estimate the
critical density of defects leading to the disappearance of the superstructure.
We have modelled the experimental results and calculated the electron density
using a DFT algorithm. The model clearly shows the development of strain along
the surface.

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The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math