スピンバルブ構造をもつ極薄CoFeフリー層の磁歪 : 磁気ヘッド

概要

論文の詳細を見る
An ultrathin CoFe free layer is very important for future high density recording head such as those using specular spin-valve films, because a CoFe free layer gives a higher MR ratio than a conventional NiFe/CoFe free layer. In order to realize a single CoFe free layer, we investigated the magnetostriction (λ_s) of an ultrathin CoFe free layer in spin-valve films. We compared the magnetostriction dependence on the underlayer structure among Cu, Ru, and Ru/Cu underlayers on a Ta buffer layer. For an Ru/Cu double-layered underlayer, λ_s becomes positively large when the Ru underlayer thickness is increased; on the other hand, it becomes negatively large when the Cu underlayer thickness is increased. This tendency can be explained by a model in which the λ_s is changed by the lattice elastic strain, where the volume ratio of Ru/Cu changes the lattice strain of an ultrathin CoFe free layer. The sensitivity of λ_s to the Cu underlayer thickness becomes large with increasing Co concentration in the CoFe free layer. This indicates that λ_s of a CoFe free layer becomes sensitive to the elastic strain with increasing Co concentration.
社団法人日本磁気学会の論文
2002-04-01