Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiferroicity in the frustrated spinel cuprate GeCu$_2$O$_4$   Different from other magnetically frustrated spinel systems,
GeCu$_{2}$O$_{4}$ is a strongly tetragonal distorted spinel cuprate in which
edge-sharing CuO$_{2}$ ribbons are running along alternating directions
perpendicular to the $c$-axis. Here, GeCu$_{2}$O$_{4}$ samples of high quality
were prepared via high pressure synthesis (at 4 GPa) and the corresponding
magnetic and dielectric properties were investigated. For the first time, we
observed a ferroelectric polarization emerging at T$_{N}$ $\sim$ 33~K. Although
the ferroelectric polarization is weak in GeCu$_{2}$O$_{4}$ ($P$ $\sim$
0.2$\mu$C/m$^{2}$), the existence of spin-induced multiferroicity provides a
strong constraint on the possible ground state magnetic structures and/or the
corresponding theoretical models of multiferroicity for GeCu$_{2}$O$_{4}$.

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The categories of this paper are: cs
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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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: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat