Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiferroic Properties of Nanocrystalline BaTiO3   Some of the Multiferroics [1] form a rare class of materials that exhibit
magnetoelectric coupling arising from the coexistence of ferromagnetism and
ferroelectricity, with potential for many technological applications.[2,3] Over
the last decade, an active research on multiferroics has resulted in the
identification of a few routes that lead to multiferroicity in bulk
materials.[4-6] While ferroelectricity in a classic ferroelectric such as
BaTiO3 is expected to diminish with the reducing particle size,[7,8]
ferromagnetism cannot occur in its bulk form.[9] Here, we use a combination of
experiment and first-principles simulations to demonstrate that multiferroic
nature emerges in intermediate size nanocrystalline BaTiO3, ferromagnetism
arising from the oxygen vacancies at the surface and ferroelectricity from the
core. A strong coupling between a surface polar phonon and spin is shown to
result in a magnetocapacitance effect observed at room temperature, which can
open up possibilities of new electro-magneto-mechanical devices at the
nano-scale.

3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph