Influence of magnetic layer thickness on magnetic, microstructural and electrical properties of CoFeB sandwiched in Ta layers

Ta [RT]/ CoFeB (2-50nm) [Ts = 500°C] /Ta [RT] films were grown on Silicon dioxide substrates by UHV magnetron sputtering system. The magnetic, microstructural and electrical properties were investigated as a function of CoFeB thickness (tCoFeB) at suitable substrate temperature (Ts). Further, we identify that, the strength of perpendicular coercivity (Hc┴)of the stacks mainly depends on the tCoFeB. Higher Hc┴ value of ≈ 564 Oe is observed for the thicker CoFeB film. The enhancement in the Hc┴ on increasing the film thickness upto 50 nm is due to the crystallization of CoFeB film at Ts = 500 °C. The morphological studies show larger grain size for thicker CoFeB film. A high value of electrical resistivity (ρ) is obtained by employing the standard four probe method, which further proves the amorphous nature of the CoFeB films. This Ta/CoFeB/Ta at Ts = 500 °C structures having high Hc┴ , large spin polarization (P) and low damping constant (α) values could be a capable candidate in the fabrication of novel spintronic devices.