Improvement of high-frequency magnetic properties of CoFeB thin film using oblique deposition for spin wave electronic devices

The use of materials with low damping coefficient and high resonant frequency in spin electronic devices means the fastest and least dissipative information transmission. We report the direct fabrication of 40-nm amorphous Co40Fe40B20 thin films on silicon substrates using magnetron sputtering and investigate the dependence of their high-frequency magnetic properties on oblique deposition. It was observed that, with an increasing inclination angle, the in-plane uniaxial magnetic anisotropy initially increased and then decreased. The phenomenon is attributed to the increased roughness of the film as the oblique deposition angle increases. When the roughness of the film reaches a certain threshold, pinning of magnetic domain walls begins to form, leading to a reduction in in-plane uniaxial magnetic anisotropy. By increasing the sputtering angle to 40° during the deposition, the in-plane uniaxial magnetic anisotropy increased from 24.4 to 554.8 Oe. Furthermore, the high-frequency magnetic properties of the CoFeB amorphous thin films were modulated, extending their resonance frequency from 2.58 to 4.76 GHz while simultaneously reducing the damping factor to 0.025.