resumo
This study investigates the nanostructure of perovskite thin films, and its influence on magnetic properties. Epitaxial thin films of perovskite La0.7Sr0.3MnO3 with thickness ranging from 13.5 nm to 320 nm were deposited on SrTiO3 (1 0 0) substrates using pulsed laser deposition techniques. X-ray diffraction, along with high-resolution transmission electron microscopy (HRTEM) investigations were carried out, and showed the presence of a second, La-rich phase in thick film. Scanning electron microscopy analysis showed thinner films to have smooth surfaces, while thicker films presented large triangular shapes emerging out of the film surface. Also HRTEM images revealed epitaxial growth for thinner films. Thicker films grow with numerous misfit dislocations leading to columnar structure, where the thickest film presents branched structure with an intermediate La-rich layer. Lattice mismatch, diffusion of Mn ions into the substrate and substituting Ti ions are known as sources of strain in films near interfaces. Magnetic properties in the structure mentioned are described by double-exchange interaction, which is very sensitive to local structure. Hence, the nanostructure of films reported here has a remarkable effect on their magnetic properties.
palavras-chave
COLOSSAL MAGNETORESISTIVE MANGANITES; PULSED-LASER DEPOSITION; DOMAIN-WALLS; EPITAXY; HETEROSTRUCTURES; DISTORTIONS; OXIDE
categoria
Physics
autores
Vaghefi, PM; Baghizadeh, A; Willinger, MG; Pereira, MJ; Mota, DA; Almeida, BG; Moreira, JA; Amaral, VS
nossos autores
Ali Baghi Zadeh
Bolseiro de pós-Doutoramento
Maria João Portela e Sá Pereira
Bolseiro de pós-Doutoramento
Pegah Mirzadeh Vaghefi
Bolseiro de pós-Doutoramento
Vitor Brás Sequeira Amaral
Professor CatedráticoGrupos
2 - nanoestruturas e cerâmicos ferróicos multifuncionais
4 - biorrefinarias, materiais de origem biológica e reciclagem
Projectos
MULTIFOX: Nanometric Probing and Modification of Multiferroic Oxides (PTDC/FIS/105416/2008)
Multiferroics and magnetoelectrics for spintronics: barriers and interfaces (PTDC/CTM/099415/2008)
agradecimentos
This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID / CTM /50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. We would like to thank the financial support from the FCT project PTDC/FIS/105416/2008 MULTIFOX and PTDC/CTM/099415/2008 grants and FCT project SFRH/BD/51140/2010 to access all microscopes in pole of electron microscopy in Aveiro University. They are also grateful to professor Joaquim Manuel Vieira for his fruitful discussions on TEM analysis and results.