Chargeordering 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 2229180, Brazil 
Abstract 
A study of the magnetocaloric properties of La1xCaxMnO3, La1xyYyCaxMnO3 and Pr1xCaxMnO3 manganites with ferromagnetic and chargeordered 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 magnetoelastic coupling effects lead to a firstorder paramagneticferromagnetic 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.
