Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spiral magnetic ordering of the Eu moments in EuNi$_{2}$As$_{2}$   The ground-state magnetic structure of EuNi$_{2}$As$_{2}$ was investigated by
single-crystal neutron diffraction. At base temperature, the Eu$^{2+}$ moments
are found to form an incommensurate antiferromagnetic spiral-like structure
with a magnetic propagation vector of $\mathit{k}$ = (0, 0, 0.92). They align
ferromagnetically in the $\mathit{ab}$ plane with the moment size of 6.75(6)
$\mu_{B}$, but rotate spirally by 165.6(1){\deg} around the $\mathit{c}$ axis
from layer to layer. The magnetic order parameter in the critical region close
to the ordering temperature, $\mathit{T_{N}}$ = 15 K, shows critical behavior
with a critical exponent of $\beta_{Eu}$ = 0.34(1), consistent with the
three-dimensional Heisenberg model. Moreover, within the experimental
uncertainty, our neutron data is consistent with a model in which the Ni
sublattice is not magnetically ordered.

21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess