Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin wave measurements over the full Brillouin zone of multiferroic
  BiFeO3   Using inelastic neutron scattering technique, we measured the spin wave
dispersion over the entire Brillouin zone of room temperature multiferroic
BiFeO3 single crystals with magnetic excitations extending to as high as 72.5
meV. The full spin waves can be explained by a simple Heisenberg Hamiltonian
with a nearest neighbor exchange interaction (J=4.38 meV), a next nearest
neighbor exchange interaction (J'=0.15 meV), and a Dzyaloshinskii-Moriya-like
term (D=0.107 meV). This simple Hamiltonian determined, for the first time, for
BiFeO3 provides a fundamental ingredient for understanding of the novel
magnetic properties of BiFeO3.

25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg