Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for small or intermediate-size polarons in the ferromagnetic
  state of manganites   Oxygen-isotope effects on the intrinsic resistivity have been studied in
high-quality epitaxial thin films of La_{0.75}Ca_{0.25}MnO_{3} and
Nd_{0.7}Sr_{0.3}MnO_{3}. We found that the residual resistivity \rho_{o}
increases by about 15(3)% upon replacing ^{16}O by ^{18}O. This provides strong
evidence for the presence of small or intermediate-size polarons in the
metallic ferromagnetic state. Furthermore, the temperature dependent part of
the resistivity at low temperatures consists of an AT^{4.5} term contributed
from 2-magnon scattering, and a B\omega_{s}/\sinh^{2}(\hbar\omega_{s}/2k_{B}T)
term which arises from scattering by a soft optical phonon mode. The absolute
magnitudes of the coefficient A and the phonon frequency \hbar\omega_{s} for
both isotope samples are in quantitative agreement with theoretical
predictions.

10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph