Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrasonic evidence of an uncorrelated cluster formation temperature in
  manganites with first-order magnetic transition at T_C   Ultrasonic attenuation and phase velocity measurements have been carried out
in the ferromagnetic perovskites La_{2/3}Ca_{1/3}MnO_3 and
La_{2/3}Sr_{1/3}MnO_3. Data show that the transition at the Curie temperature,
T_C, changes from first- to second-order as Sr replaces Ca in the perovskite.
The compound with first-order transition shows also another transition at a
temperature T* > T_C. We interpret the temperature window T_C < T < T* as a
region of coexistence of a phase separated regime of metallic and insulating
regions, in the line of recent theoretical proposals.

21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex