Effect of magnetic annealing on IrMn based spin valve materials with SAF structure

Abstract

IrMn based spin valve materials with SAF (CoFe/Ru/CoFe) structure were deposited by magnetron sputtering system. HRTEM, AFM and XPS techniques were utilized to characterize the microstructures and composition of the spin valve materials. First, the deposited materials were annealed at 200°C, 245°C, 255°C and 265°C for 4 h in vacuum (≤10-5 Pa). It was found that obvious interlayer diffusion was happened after being annealed at 265°C, which resulted in the decrease of magneto-resistance (MR) ratio. Set field annealing temperature at 245°C, the spin valve materials were annealed at fields of 80, 160, 240, 400 and 560 kA/m along the pinning direction for 4 h in vacuum, respectively. It was found that the MR ratio of the materials declined to 5.87% and 6.31% from 8.80% after 80 kA/m and 160 kA/m annealing, respectively. After 240 kA/m annealing, the MR ratio became 7.91%. After 400 kA/m annealing, the MR ratio increased to 9.89%. After 560 kA/m annealing, the MR ratio reached 10.79%, which was increased by 22.6% as compared with the material before annealing.