Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Raman spectra in epitaxial thin films $La_{1-x}Ca_xMnO_3$ (x = 0.33,
  0.5) grown on different substrates   Raman spectra of LCMO films grown on LAO (001), STO (001), and MgO (001)
substrates were studied at different temperatures. The effect of temperature,
doping level and strain on Raman spectra are discussed in detail. With
decreasing temperature, the changes of Raman spectra are correlated with the
disorder-order transition, shuch as: paramagnetism to ferromagnetism, and
charge-ordering. The strain induced by lattice-substrate mismatch affects the
Raman spectra strongly. The mode induced by disorder of oxygen defects is
apparently observed in $La_{0.67}Ca_{0.33}MnO_3$ film on STO due to the larger
tensile strain. While this mode can not be seen in the Raman spectra for the
films on LAO and MgO. A strong unsigned mode at about 690 $cm^{-1}$ is observed
in all films except for $La_{0.67}Ca_{0.33}MnO_3$ film on LAO, which is not
observed in bulk sample easily. It suggests that the mode is closely related to
the strain.

1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin