Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron spin resonance in the $S$=1/2 quasi-one-dimensional
  antiferromagnet with Dzyaloshinskii-Moriya interaction BaCu$\_2$Ge$\_2$O$\_7$   We have investigated the electron spin resonance (ESR) on single crystals of
BaCu$\_2$Ge$\_2$O$\_7$ at temperatures between 300 and 2 K and in a large
frequency band, 9.6 -134 GHz, in order to test the predictions of a recent
theory, proposed by Oshikawa and Affleck (OA), which describes the ESR in a
$S$=1/2 Heisenberg chain with the Dzyaloshinskii-Moriya interaction. We find,
in particular, that the ESR linewidth, $\Delta H$, displays a rich temperature
behavior. As the temperature decreases from $T\_{max}/2\approx $ 170 K to 50 K,
$\Delta H$ shows a rapid and linear decrease, $\Delta H \sim T$. At low
temperatures, below 50 K, $\Delta H$ acquires a strong dependence on the
magnetic field orientation and for $H \| c$ it shows a $(h/T)^2$ behavior which
is due to an induced staggered field $h$, according to OA's prediction.

25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph