Ferromagnetic free layer, preparation method and application thereof

A ferromagnetic free layer, comprising a magnetic film alloy, wherein the magnetic film alloy comprises a plurality layers of laminated films, and a thickness of each of the films decreases gradually from a first end to a second end of the magnetic film alloy;

• the films include heavy metal films and ferromagnetic metal films, the heavy metal films and the ferromagnetic metal films are disposed alternatively;
• thicknesses of the heavy metal films increase or decrease successively from a top layer to a bottom layer, and a thickness of each of the ferromagnetic metal films is the same;
• or, a thickness of each of the heavy metal films is the same, and thicknesses of the ferromagnetic metal films increase or decrease successively from a top layer to a bottom layer;
• or, the thicknesses of the heavy metal films increase successively from the top layer to the bottom layer, and the thicknesses of the ferromagnetic metal films decrease successively from the top layer to the bottom layer;
• or, the thicknesses of the heavy metal films decrease successively from the top layer to the bottom layer, and the thicknesses of the ferromagnetic metal films increase successively from the top layer to the bottom layer.