Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of an inter-sublattice exchange magnon in CoCr$_2$O$_4$ and
  analysis of magnetic ordering   We report on an investigation of optical properties of multiferroic
CoCr$_{2}$O$_{4}$ at terahertz frequencies in magnetic fields up to 30 T. Below
the ferrimagnetic transition (94 K), the terahertz response of
CoCr$_{2}$O$_{4}$ is dominated by a magnon mode, which shows a steep
magnetic-field dependence. We ascribe this mode to an exchange resonance
between two magnetic sublattices with different $g$-factors. In the framework
of a simple two-sublattice model (the sublattices are formed by Co$^{2+}$ and
Cr$^{3+}$ ions), we find the inter-sublattice coupling constant, $\lambda = -
(18 \pm 1)$ K, and trace the magnetization for each sublattice as a function of
field. We show that the Curie temperature of the Cr$^{3+}$ sublattice,
$\Theta_{2}$ = $(49 \pm 2)$ K, coincides with the temperature range, where
anomalies of the dielectric and magnetic properties of CoCr$_{2}$O$_{4}$ have
been reported in literature.

24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th