Interfacial effects on magnetostriction of CoFeB∕AlOx∕Co junction

Saturation magnetostriction (λs) of CoFeB∕AlOx∕Co magnetic tunnel junctions (MTJs) has been measured. There are three kinds of MTJs in this study, i.e., glass∕CoFeB(tA)∕AlOx(δto)∕Co(tB) with tA+tB=150Å; tA=100, 75, and 50Å; and δto=0–30Å. When plotting λs as a function of δto, the curve is concave up. We also investigated the compositional distribution of Fe, Al, and O across the tunneling part of the CoFeB(75Å)∕AlOx∕Co(75Å) junction. Based on these results, we propose a model to describe how the total λs is affected by the CoFeB∕AlOx and AlOx∕Co interfaces.