Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Artificial "spin ice" in a geometrically frustrated lattice of nanoscale
  ferromagnetic islands   We report an artificial geometrically frustrated magnet based on an array of
lithographically fabricated single-domain ferromagnetic islands. The islands
are arranged such that the dipole interactions create a two-dimensional
analogue to spin ice. Images of the magnetic moments of individual elements in
this correlated system allow us to study the local accommodation of
frustration. We see both ice-like short-range correlations and an absence of
long-range correlations, behaviour which is strikingly similar to the
lowtemperature state of spin ice. These results demonstrate that artificial
frustrated magnets can provide an uncharted arena in which the physics of
frustration can be directly visualized.

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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: nlin
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph