Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical Analysis of the "Double-q" Magnetic Structure of CeAl2   A model involving competing short-range isotropic Heisenberg interactions is
developed to explain the "double-q" magnetic structure of CeAl$_2$. For
suitably chosen interactions, terms in the Landau expansion quadratic in the
order parameters explain the condensation of incommensurate order at
wavevectors in the star of (1/2 $-\delta$, 1/2 $+\delta$, 1/2)$(2\pi/a)$, where
$a$ is the cubic lattice constant. We show that the fourth order terms in the
Landau expansion lead to the formation of the so-called "double-q" magnetic
structure in which long-range order develops simultaneously at two
symmetry-related wavevectors, in striking agreement with the magnetic structure
determinations. Based on the value of the ordering temperature and of the
Curie-Weiss $\Theta$ of the susceptibility, we estimate that the nearest
neighbor interaction $K_0$ is ferromagnetic, with $K_0/k=-11\pm 1$K and the
next-nearest neighbor interaction $J$ is antiferromagnetic with $J/k=6 \pm 1$K.
We also briefly comment on the analogous phenomenon seen in the similar system
TmS.

1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int