Effects of boron composition on tunneling magnetoresistance ratio and microstructure of CoFeB/MgO/CoFeB pseudo-spin-valve magnetic tunnel junctions

摘要

The effect of B concentration on the tunneling magnetoresistance (TMR) of (Co_(25)Fe_(25))_(100-x) B_x/MgO/(Co)(25)Fe_(75))_(100-x)B_x (x = 22 and 33) pseudo-spin-valve (P-SV) magnetic tunnel junctions (MTJs) was investigated. The TMR ratios for optimally annealed MTJs with x = 22 and 33 were 340% and 170%, respectively, at room temperature. High resolution transmission electron microscopy (HRTEM) observation showed a weaker (001) texture in the MgO barrier in the MTJ with v=33. The bottom electrode was not fully crystallized even with a considerable amount of B in the (Co_(25)Fe_(75))_(67)B_(33), while good epitaxy was observed between (001) textured MgO and (Co_(25)Fe_(75))_(78)B_(22) electrodes.