Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of the helical spin crystal: a candidate for the partially
  ordered state of MnSi   MnSi is an itinerant magnet which at low temperatures develops a helical spin
density wave. Under pressure it undergoes a transition into an unusual
partially ordered state whose nature is debated. Here we propose that the
helical spin crystal (the magnetic analog of a solid) is a useful starting
point to understand partial order in MnSi. We consider different helical spin
crystals and determine conditions under which they may be energetically
favored. The most promising candidate has bcc structure and is reminiscent of
the blue phase of liquid-crystals in that it has line-nodes of magnetization
protected by symmetry. We introduce a Landau theory to study the properties of
these states, in particular the effect of crystal anisotropy, magnetic field
and disorder. These results compare favorably with existing data on MnSi from
neutron scattering and magnetic field studies. Future experiments to test this
scenario are also proposed.

1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess