In search of zero magnetostrictive CoFeB/AlO_x/Co junctions

摘要

This study examines two kinds (as-deposited and annealed) of magnetic tunnel junctions (MTJs): glass/CoFeB(t_A)/AlO_x(δt_o)/Co(t_B) with t_A + t_B = 150 A, t_B = 50, 70, 75, and 100 A; and δt_o = 0-30 A. After field-annealing these MTJs at T_A = 250 ℃ for 1 h, the concave up feature, originally existing in the magnetostriction (λ_s) vs. δt_o curve, turns into the fluctuating feature. We have successfully determined the composition of the zero-λ_s. MTJ, (t_B~o) or t_B~o, with or without annealing, as a function of δt0, which appears to be important technical information.