Substrate, annealing, and Mn excess effects on La-Ca-MnO3 thin films grown by metalorganic chemical vapor deposition: A way to room-temperature T-c

• Tipo: Artigo em Revista Científica Internacional
• Data: 1999

Autores

Tavares, Pedro B. (Autor) Outra; Amaral, V. S. (Autor) Outra; Araújo, João Pedro (Autor) Outra; Sousa, João Bessa (Autor) FCUP; Lourenço, A. A C S (Autor) Outra; Vieira, Joaquim Manuel (Autor) Outra

Revista

Título: Journal of Applied Physics

Vol. 85

Páginas: 5411-5413

ISSN: 0021-8979

Editora: American Institute of Physics

Indexação

ISI Web of Knowledge - 15 Citações

Scopus - 16 Citações

Outras Informações

ID Authenticus: P-001-4KV

DOI: 10.1063/1.369994

Abstract (EN): Oriented thin films of the La-Ca-MnO3 system with several Mn-excess compositions were prepared by aerosol-assisted metalorganic chemical vapor deposition. Depositions both on MgO (100) and LaAlO3 (100) substrates were performed at temperatures between 700 and 800 degrees C, with 30 min in situ oxygen annealing at the deposition temperature. The films deposited on LaAlO3 have much better structural quality with rocking curves of 0.3-0.7 full width at half maximum and higher T-c. For films with Mn excess, an ex situ annealing (800 degrees C for 1 h in flowing oxygen) increases T-c dramatically, from 180-190 K to values in the range 240-296 K, above the maximum T-c of the stoichiometric, optimally doped La0.67Ca0.33MnO3 composition. This behavior may be associated with the presence of La vacancies, which act as self-dopants, and whose role is enhanced after suitable annealing. The films present high magnetoresistance values in the vicinity of the critical temperatures: at 7 kOe, 32% for a film with T-c = 279 K and 13% for a film with T-c = 296 K. The magnetic properties of the films on MgO were degraded by annealing, probably due to Mg diffusion to the film. (C) 1999 American Institute of Physics. [S0021-8979(99)49708-7].

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 3