Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transverse instability and universal decay of spin spiral order in the
  Heisenberg model   We analyze the stability of spin spiral states in the two-dimensional
Heisenberg model. Our analysis reveals that the SU(2) symmetric point hosts a
dynamic instability that is enabled by the existence of energetically favorable
transverse deformations---both in real and spin space---of the spiral order.
The instability is universal in the sense that it applies to systems with any
spin number, spiral wavevector, and spiral amplitude. Unlike the Landau or
modulational instabilities which require impurities or periodic potential
modulation of an optical lattice, quantum fluctuations alone are sufficient to
trigger the transverse instability. We analytically find the most unstable mode
and its growth rate, and compare our analysis with phase space methods. By
adding an easy plane exchange coupling that reduces the Hamiltonian symmetry
from SU(2) to U(1), the stability boundary is shown to continuously interpolate
between the modulational instability and the transverse instability. This
suggests that the transverse instability is an important mechanism that hinders
the formation of a spin superfluid, even in the presence of strong exchange
anisotropy.

3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex