Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orientation of the intra-unit-cell magnetic moment in the high-Tc
  superconductor HgBa2CuO$_{4+{\delta}}$   Polarized-neutron diffraction experiments (PND) have revealed that the
pseudogap state of the cuprates exhibits unusual intra-unit-cell (IUC)
magnetism. At a qualitative level, the data indicate a moment direction that is
neither perpendicular nor parallel to the CuO2 layers, yet an accurate
measurement of a structurally simple compound has been lacking. Here we report
PND results with unprecedented accuracy for the IUC magnetic order in the
simple-tetragonal single-CuO$_2$-layer compound HgBa2CuO$_{4+{\delta}}$. At the
transition temperature, we find evidence for magnetic critical scattering. Deep
in the ordered state, we determine the moment direction to be 70{\deg} $\pm$
10{\deg} away from the normal to the CuO$_2$ layers, which rules out both
purely planar loop currents and high-symmetry Dirac multipoles, the two most
prominent theoretical proposals for the microscopic origin of the IUC
magnetism. However, the data are consistent with Dirac multipoles of lower
symmetry or, alternatively, with a particular configuration of loop currents
that flow on the faces of the CuO$_6$ octahedra.

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The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
18
The categories of this paper are: econ
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg