Determination of correlation between magnetic and structural properties in nano-scale irmn/cofe thin film systems for magnetic storage systems

In this study, the effect of pulsing frequency (10, 20, 30 and 50 kHz) on exchange bias properties of Ta(5nm)/Ru (25nm)/Ta(5nm)/NiFe(6nm)/IrMn(10nm)/CoFe (2nm)/Ta(5nm) thin film stack, where the pulsing frequecy was changed during NiFe deposition was investigated. Then the frequency change was correlated to IrMn grain size and antiferromagnetic/ferromagnetic interface?s magnetic properties. Structural characterization techniques such as X-ray diffraction, reflection, grazing angle and rocking curve techniques were utilized. It was found that 10kHz NiFe sample has the largest IrMn grain size and lattice constant. The same sample showed the highest Ru and IrMn crystalline texture ratio. According to the magnetic characterizations, Hc fields of CoFe and NiFe layers were decreased where CoFe free layer?s Hex field remained constant. Therfore, the highest Hex/Hc ratio was obtained from the 10kHz sample. However, the 50kHz sample, having one of the smallest grain sizes, showed highest exchange bias coupling energy (Jk). Consequently, it is understood that the domain structure changes with increasing grain size have an effect on the exchange bias properties. The second sample series (Ta(5nm)/Ru(10nm)/Ta(5nm)/NiFe(6nm)/IrMn(10nm)/ CoFe (2nm)/Ta(5nm)) was studied for investigating the pulsing reverse time on the interface roughness values inside the whole exchange bias system. It was observed that, the Ru/Ta, NiFe/IrMn and IrMn/CoFe interface roughnesses depend on the Ru arc counts during deposition.