Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple-Q Instability by (d-2)-dimensional Connections of Fermi
  Surfaces   We propose a general mechanism of multiple-Q ordering with noncollinear and
noncoplanar spin textures in itinerant magnets. By analyzing the fourth-order
perturbation with respect to the spin-charge coupling, we find that the
instability toward multiple-Q ordering is caused by (d-2)-dimensional
connections of the Fermi surfaces in the extended Brillouin zone by the
multiple-Q wave vectors: zero(one)-dimensional point (line) connections in the
two(three)-dimensional systems. The instabilities are obtained as the "fixed
points" in the two-parameter flow diagram, irrespective of lattice structures.
The hidden Fermi surface instability provides a universal origin of
noncollinear and noncoplanar instabilities common to frustrated and
unfrustrated lattice systems.

16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph