Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective field theories and spin-wave excitations in helical magnets   We consider two classes of helical magnets. The first one has magnetic
ordering close to antiferromagnet and the second one has magnetic ordering
close to ferromagnet. The first case is relevant to cuprate superconductors and
the second case is realized in FeSrO$_3$ and FeCaO$_3$. We derive the effective
field theories for these cases and calculate corresponding excitation spectra.
We demonstrate that the "hourglass" spin-wave dispersion observed
experimentally in cuprates is a fingerprint of the "antiferromagnetic spin
spiral state". We also show that quantum fluctuations are important for the
"ferromagnetic spin spiral", they influence qualitative features of the
spin-wave dispersion.

11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics