Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Possible evidence for electromagnons in multiferroic manganites   Magnetodielectric materials are characterized by a strong coupling of
magnetic and dielectric properties and in rare cases simultaneously exhibit
both, magnetic and polar order. Among other multiferroics, TbMnO3 and GdMnO3
reveal a strong magneto-dielectric (ME) coupling and as a consequence
fundamentally new spin excitations exist: Electro-active magnons, or
electromagnons, i. e. spin waves which can be excited by ac electric fields.
Here we show that these excitations appear in the phase with an incommensurate
(IC) magnetic structure of the manganese spins. In external magnetic fields
this IC structure can be suppressed and the electromagnons are wiped out,
thereby inducing considerable changes in the index of refraction from dc up to
THz frequencies. Hence, besides adding a new creature to the zoo of fundamental
excitations, the refraction index can be tuned by moderate magnetic fields,
which allows the design of a new generation of optical switches and
optoelectronic devices.

36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol