Phase separation in Cu/sub 90/Co/sub 10/ high-magnetoresistance materials

• Autor(a) principal: Miranda, Marines Grande Malcum
• Data de Publicação: 2003
• Outros Autores: Estevez Rams, Ernesto, Martinez Pino, Gerardo Guido, Baibich, Mario Norberto
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/104260
• topic: Ligas de cobalto; Ligas de cobre; Separação de fases; Decomposicao spinodal; Microscopia eletrônica de transmissão; Análise química por raios x

The relation between giant magnetoresistance ~GMR! and phase separated nanostructures in Cu90Co10 is studied using magnetotransport measurements together with transmission electron microscopy and x-ray microanalysis. The samples were melt-spun ribbons isochronally annealed up to 873 K, and all show in their grains a homogeneous spinodal decomposition characterized by long parallel Co-excess stripes. These stripes have 40-nm modulation periods and develop along the crystalline directions of each grain. Different anneals do not change appreciably the observed microstructures, while the magnetoresistance is initially enhanced by a factor of 2, followed by a 35% drop above 823 K. The latter coincides with the observation of a secondary lamellar decomposition of 4 nm modulation length. We propose that the GMR effects in CuCo alloys originate from these nanoscopic modulations of the constituents induced by nonequilibrium processes.