Magnetoresistance effect element, magnetic head and magnetic recording and/or reproducing system

A magnetoresistance effect element comprising:

• a magnetoresistance effect film including a magnetization fixed layer having a ferromagnetic film in which the direction of magnetization is substantially fixed to one direction, a magnetization free layer having a ferromagnetic film in which the direction of magnetization varies in response to an external magnetic field, and a non-magnetic intermediate layer provided between the magnetization fixed layer and the magnetization free layer;
• a pair of electrodes which are electrically connected to the magnetoresistance effect film and configured to apply a current in a direction perpendicular to the plane of the magnetoresistance effect film;
• and
• a resistance regulating layer containing an oxide, a nitride, a fluoride, a carbide or a boride;
• the resistance regulating layer formed in the non-magnetic intermediate layer or on the interface between the non-magnetic intermediate layer and at least one of the magnetization fixed layer and the magnetization free layer, and
• the ferromagnetic film of at least one of the magnetization fixed layer and the magnetization free layer comprising a stacked structure which has at least a non-magnetic layer and two first magnetic layers sandwiching the non-magnetic layer, magnetizations of the first magnetic layers are substantially parallel to each other and substantially arranged in the same direction.