Magnetoresistance effect element comprising nano-contact portion not more than a mean free path and magnetic head utilizing same

A magnetic head comprising:

• a magnetoresistance effect element having a lamination structure;
• electrodes disposed on both sides of the lamination structure of the magnetoresistance effect element;
• a pair of shield members disposed on outside surfaces of the electrodes, respectively, said magnetoresistance effect element comprising:
• a free layer composed of a ferromagnetic layer;
• a pinned layer composed of a ferromagnetic layer;
• and at least one nano-contact portion disposed between the free layer and the pinned layer,
• an insulating layer formed of an insulating material and disposed between the free layer and the pinned layer, said insulating layer and said the nano-contact portion forming an intermediate layer between the free layer and the pinned layer;
• and
• a conductive layer disposed at least one of a portion between the free layer and the intermediate layer including the insulating layer and the nano-contact portion and a portion between the pinned layer and the intermediate layer including the insulating layer and the nano-contact portion
• wherein said nano-contact portion has a dimension, including at least one of a length in a layer lamination direction of the magnetoresistance effect element and a length in a direction normal to the layer lamination direction, being not more than a mean free path and said nano-contact portion is provided, in an inside portion thereof, with—a magnetic wall composed of one of a Bloch magnetic wall, a Nëel magnetic wall and a combination wall thereof.