Interlayer and Interfacial Exchange Coupling of IrMn Based MTJ

Abstract

As deposited and annealed MTJs with the structure of <TEX>$Ta(5 nm)/Cu(10 nm)/Ta(5 nm)/Ni_{80}Fe_{20}(2 nm)/Cu(5 nm)/ Ir_{25}Mn_{75}(10 nm)/Co_{70}Fe_{30}(2.5 nm)/Al-O/Co_{70}Fe_{30}(2.5nm)/Ni_{80}Fe_{20}(t)/Ta(5nm)/Ni_{80}Fe_{20}(t)/Ta(5 nm)$</TEX>, where t=10, 30, 60 and 100 nm were characterized by XRD and magnetic hysteresis loops measurements. The XRD measurements were done in grazing incidence <TEX>$(GID scan-2{\theta})$</TEX> and <TEX>${\theta}-2{\theta}$</TEX> geometry, by rocking curve <TEX>$(scan-{\omega})$</TEX> and pole figures in order to establish correlation between texture and crystallites size and magnetic parameters of exchange biased and interlayer coupling. The variations of shifting and coercivity field of free and pinned layers after annealing in <TEX>$300^{\circ}C$</TEX> correlate with the improvement of ［111］ texture and grains size of <TEX>$Ni_{80}Fe_{20}$</TEX> and <TEX>$Ir_{25}Mn_{75}$</TEX> respectively. The exchange biased and the coercivity fields of the pinned layer linearly increased with increasing grain size of <TEX>$Ir_{25}Mn_{75}$</TEX>, The reciprocal proportionality between interlayer coupling and coercivity fields of the free layer and grain size of <TEX>$Ni_{80}Fe_{20}$</TEX> was found. The enhancement of interlayer coupling between pinned and free layers, after annealing treatment, indicates on the correlated in-phase roughness of dipolar interacting interfaces due to increase of crystallites size of <TEX>$Ni_{80}Fe_{20}$</TEX>.