Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Helical nuclear spin order in two-subband quantum wires   In quantum wires, the hyperfine coupling between conduction electrons and
nuclear spins can lead to a (partial) ordering of both of them at low
temperatures. By an interaction-enhanced mechanism, the nuclear spin order,
caused by RKKY exchange, acts back onto the electrons and gaps out part of
their spectrum. In wires with two subbands characterized by distinct Fermi
momenta kF1 and kF2, the nuclear spins form a superposition of two helices with
pitches {\pi}/kF1 and {\pi}/kF2, thus exhibiting a beating pattern. This order
results in a reduction of the electronic conductance in two steps upon lowering
the temperature.

8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
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The categories of this paper are: eess
16
The categories of this paper are: stat