Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic frustration in the spinel compounds Ge Co_2 O_4 and Ge Ni_2 O_4   In both spinel compounds GeCo$_2$O$_4$ and GeNi$_2$O$_4$ which order
antiferromagnetically (at $T_N = 23.5 K$ and $T_{N_1} = 12.13 K$, $T_{N_2} =
11.46 K$) with different Curie Weiss temperatures ($T_{CW}$=80.5 K and -15 K),
the usual magnetic frustration criterion $f=|T_{CW}|/T_N>>1$ is not fulfilled.
Using neutron powder diffraction and magnetization measurements up to 55 T,
both compounds are found with a close magnetic ground state at low temperature
and a similar magnetic behavior (but with a different energy scale), even
though spin anisotropy and first neighbor exchange interactions are quite
different. This magnetic behavior can be understood when considering the main
four magnetic exchange interactions. Frustration mechanisms are then
enlightened.

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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga