Charge-ordering and magnetoelastic coupling effects on the magnetocaloric properties of manganites
|Vitor S. Amaral 2, Mario S. Reis 1,2, A. M. Gomes 1, Joao P. Araujo 3, P. B. Tavares 4, J. S. Amaral 2, I. S. Oliveira 1|
1. Centro Brasileiro de Pesquisas Físicas (CBPF), R. Dr. Xavier Sigaud 150 Urca, Rio de Janeiro 2229-180, Brazil
A study of the magnetocaloric properties of La1-xCaxMnO3, La1-x-yYyCaxMnO3 and Pr1-xCaxMnO3 manganites with ferromagnetic and charge-ordered states is presented. The ferromagnetic Lanthanum manganites show a negative entropy change peak DS under the application of a magnetic field at the Curie temperature. However, the magneto-elastic coupling effects lead to a first-order paramagnetic-ferromagnetic transition and an increased DS compared to simple ferromagnets. This effect is analysed in the framework of the Landau theory of phase transitions which shows a comparable influence of the magnetoelastic couplings and the ordinary magnetic ordering effect.
Presentation: oral at E-MRS Fall Meeting 2003, Symposium D, by Vitor S. Amaral
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-27 18:31 Revised: 2009-06-08 12:55