Scaling behavior of nearly first order magnetic phase transitions

Autor(es)

Ferreira, P. M. G. L. ^[1] ; Souza, J. A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09090400 Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF PHYSICS-CONDENSED MATTER; v. 23, n. 22 JUN 8 2011.
• Citações Web of Science: 3

Resumo

A scaling behavior between heat capacity C(P){*} and thermal expansion coefficient times temperature Omega T lambda, where. is a scale factor, is obtained for ferromagnetic La(1-x)Ca(x)MnO(3) with x = 0.20, 0.25, 0.30, 0.34, 0.40, and 0.45 compounds. The pressure derivative of the magnetic phase transition temperature obtained through a scaling method is in good agreement with experimental results for all samples. The critical exponents associated with the specific heat (alpha) for x = 0.25, 0.30, and 0.34 are very close to the phase boundary where continuous phase transitions become discontinuous. This is attributed to strong coupling among the spin, charge, and lattice degrees of freedom, which indicates that the magnetization alone would be a poor choice for the order parameter in these systems. Based on thermodynamic arguments, a phase diagram with diverging, cusp-like, near first order, and first order phase transitions is presented. (AU)

• Processo FAPESP: 09/18618-5 - Síntese de materiais e caracterização das suas propriedades termodinâmicas e transporte elétrico
• Beneficiário: José Antonio Souza
• Modalidade de apoio: Auxílio à Pesquisa - Regular