Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the magnetoelastic and magnetoelectric couplings across the
  antiferromagnetic transition in multiferroic BiFeO3   Clear anomalies in the lattice thermal expansion (deviation from linear
variation) and elastic properties (softening of the sound velocity) at the
antiferromagnetic-to-paramagnetic transition are observed in the prototypical
multiferroic BiFeO3 using a combination of picosecond acoustic pump-probe and
high-temperature X-ray diffraction experiments. Similar anomalies are also
evidenced using first-principles calculations supporting our experimental
findings. Those calculations in addition to a simple Landau-like model we also
developed allow to understand the elastic softening and lattice change at T_N
as a result of magnetostriction combined with electrostrictive and
magnetoelectric couplings which renormalize the elastic constants of the
high-temperature reference phase when the critical T_N temperature is reached.

27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ