Issue |
Europhys. Lett.
Volume 58, Number 1, April 2002
|
|
---|---|---|
Page(s) | 42 - 48 | |
Section | General | |
DOI | https://doi.org/10.1209/epl/i2002-00603-9 | |
Published online | 01 August 2002 |
Evidences for Tsallis non-extensivity on CMR manganites
1
Centro Brasileiro de Pesquisas Físicas - Rua
Dr. Xavier Sigaud 150 Rio de Janeiro-RJ 22290-180, Brazil
2
Departamento de Física, Universidade Federal do
Espirito Santo Vitória-ES, 2906-900, Brazil
Corresponding author: marior@cbpf.br
Received:
1
October
2001
Accepted:
14
January
2002
We found, from the analysis of M
vs.
T curves of
some manganese oxides (manganites), that these systems do not
follow the traditional Maxwell-Boltzmann statistics, but the
Tsallis statistics, within the normalized formalism.
Curves were calculated within the mean-field approximation, for
various ferromagnetic samples and the results were compared to
measurements of our own and to various other authors's published
data, chosen at random from the literature. The agreement between
the experimental data and calculated Mq
vs.
curve, where
is an effective temperature,
is excellent for all the compounds. The entropic parameter, q,
correlates in a simple way with the experimental value of
, irrespective of the chemical composition of the compounds,
heat treatment or other details on sample preparation. Examples
include q<1 (superextensivity), q=1 (extensivity) and q>1
(subextensivity) cases.
PACS: 05.90.+m – Other topics in statistical physics, thermodynamics, and nonlinear dynamical systems / 05.50.+q – Lattice theory and statistics (Ising, Potts, etc.) / 75.70.Pa – Giant magnetoresistance
© EDP Sciences, 2002
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