Structural and Magnetic Properties of Cr-diluted CoFeB

Abstract

The crystallization process and the magnetization of Cr diluted CoFeB was investigated in both ribbon samples and thin film samples with Cr content up to 30 at. %. A primary crystallization of bcc phase from an amorphous precursor in ribbon samples was observed when the annealing temperature rose to between 421 ˚C and 456 ˚C, followed by boron segregation at temperatures between 518 ˚C and 573 ˚C. The two onset crystallization temperatures showed strong dependences on both Cr and B concentrations. The impact of Cr concentration on the magnetic properties including a reduced saturation magnetization and an enhanced coercive field was also observed. The magnetizations of both ribbon samples and thin film samples were well fitted using the generalized Slater-Pauling curve with modified moments for B (-0.94 μB) and Cr (-3.6 μB). Possible origins of the enhanced coercive field were also discussed. We also achieved a damping parameter in CoFeCrB thin films at the same level as Co40Fe40B20, much lower than the value reported for CoFeCrB films previously. The results suggest a possible advantage of CoFeCrB in reducing the critical switching current density in Spin Transfer Torque Random Access Memory (STT-RAM).

Description
Keywords
Magnetic moments, Boron, Magnetic annealing, X-ray diffraction, Amorphous state, Crystallization, Borides, Coercive force, Magnetic films, Thin film structure
Citation
Cui, Y., et al. (2013): Structural and Magnetic Properties of Cr-diluted CoFeB, Journal of Applied Physics, 114(15).