TEM characterization of Co-Al-O nano-granular TMR film

Co-Al-O film was fabricated using the reactive r.f. magnetron sputtering te chnique. A maximum magnetoresistance (MR) of approximately 7% was establish ed through optimizing the sputter deposition conditions such as sputter pow er and gas flow rate. TEM characterization of the film revealed a nano-gran ular structure that consisted of ferromagnetic grains with grain diameters on the order of several nm together with non-magnetic grain boundary layers with the thickness on the order of less than 1 nm. The large MR was attrib uted to electron tunneling thorough this very thin grain boundary layer bet ween individual ferromagnetic grains. (C) 2001 Kluwer Academic Publishers.