Magnetoresistance effect element having a nonmagnetic intermediate layer having a two-dimensional fluctuation of resistance

Abstract

A magnetoresistance effect element comprises a magnetoresistance effect film including a magnetically pinned layer whose direction of magnetization is pinned substantially in one direction, a magnetically free layer whose direction of magnetization changes in response to an external magnetic field, and a nonmagnetic intermediate layer located between the pinned layer and the free layer; and a pair of electrodes electrically connected to said magnetoresistance effect film to supply a sense current perpendicularly to a film plane of said magnetoresistance effect film. The intermediate layer has a first layer including a first region whose resistance is relatively high and second regions whose resistance is relatively low. The sense current preferentially flows through the second regions when the current passes the first layer. Alternatively, the concentration of oxygen in the first layer may have a two-dimensional fluctuation, and a first region where the concentration of oxygen is equal to or higher than 40 atomic % and a second region where the concentration of oxygen is equal to or lower than 35 atomic % may be provided in the first layer.