Tricritical points in La-based ferromagnetic manganites

• Tipo: Artigo em Revista Científica Internacional
• Data: 2003

Autores

Amaral, V. S. (Autor) Outra; Araújo, João Pedro (Autor) FCUP; Pogorelov, Yu G G (Autor) FCUP; Sousa, João Bessa (Autor) FCUP; Tavares, Pedro B. (Autor) Outra; Vieira, Joaquim Manuel (Autor) Outra; Algarabel, Pedro A. (Autor) Outra; Ibarra, Manuel Ricardo (Autor) Outra

Revista

Título: Journal of Applied Physics

Vol. 93

Páginas: 7646-7648

ISSN: 0021-8979

Editora: American Institute of Physics

Indexação

ISI Web of Knowledge - 18 Citações

Scopus - 19 Citações

Outras Informações

ID Authenticus: P-000-GN0

DOI: 10.1063/1.1558271

Abstract (EN): A detailed study of the magnetization M(H,T) of manganites near T-C is presented. Analysis, in the framework of Landau theory of phase transitions (G=G(0)+1/2AM(2)+1/4BM(4)+1/6CM(6)-MH) reveals that for La0.67Ca0.33MnO3 (T-C=267 K), La0.8MnO3 (T-C=250 K), and La0.60Y0.07Ca0.33MnO3 (T-C=150 K) the phase transition is first-order and the B coefficient is temperature dependent, negative near T-C. In field (H<H-C*) and temperature (T-C<T<T-C*) ranges, below the critical point of the first-order phase transition, clear features are found, with hysteresis. For La0.60Y0.07Ca0.33MnO3, H-C*similar to20 kOe, DeltaT=T-C*-T(C)similar to20 K. For La0.67Ca0.33MnO3, on the other hand, H-C(*) is only 250 Oe and DeltaT<1 K. These effects are related with electronic and elastic energy contributions coupled to the magnetic order parameter. The analysis of the vanishing of B above T-C suggests that a tricritical point should occur at T&SIM;310 K, in agreement with the temperature at which the magnetic and structural transitions in La-0.7(Ca1-ySry)(0.3)MnO3 coincide. (C) 2003 American Institute of Physics.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 3