Ferromagnetic free layer, preparation method and application thereof

A preparation method of a ferromagnetic free layer, comprising:

• alternatively preparing heavy metal films and ferromagnetic metal films in a misaligned growth method, such that the heavy metal films and the ferromagnetic metal films are laminated in a vertical direction z and to obtain a ferromagnetic free layer with a first horizontal direction y and a second horizontal direction x perpendicular to the first horizontal direction y, wherein a thickness of each of the films decreases gradually from a first end to a second end of the magnetic film alloy in the first horizontal direction y, thicknesses of the heavy metal films at a same cross section of the ferromagnetic free layer, which is taken parallel to x-z plane at any position of the ferromagnetic free layer, increase or decrease successively from a top layer to a bottom layer, and a thickness of each of the ferromagnetic metal films at the same cross section is the same;
• or, a thickness of each of the heavy metal films at the same cross section is the same, and thicknesses of the ferromagnetic metal films at the same cross section increase or decrease successively from the top layer to the bottom layer;
• or, the thicknesses of the heavy metal films at the same cross section increase successively from the top layer to the bottom layer, and the thicknesses of the ferromagnetic metal films at the same cross section decrease successively from the top layer to the bottom layer;
• or, the thicknesses of the heavy metal films at the same cross section decrease successively from the top layer to the bottom layer, and the thicknesses of the ferromagnetic metal films at the same cross section increase successively from the top layer to the bottom layer,
• wherein each of the ferromagnetic metal films and the heavy metal films is formed through obliquely sputtering for predetermined sputtering times by a magnetron sputtering apparatus arranged at a predetermined oblique angle.

A ferromagnetic free layer, comprising a magnetic film alloy, wherein the magnetic film alloy comprises a plurality layers of laminated films, which are formed through obliquely sputtering for respective sputtering times by a magnetron sputtering apparatus arranged at a predetermined oblique angle so that a thickness of each of the films decreases gradually from a first end to a second end of the magnetic film alloy;

• the films comprise heavy metal films and ferromagnetic metal films, the heavy metal films and the ferromagnetic metal films are disposed alternatively;
• sputtering times of the heavy metal films increase or decrease successively from a top layer to a bottom layer, and sputtering times of ferromagnetic metal films are the same;
• or, the sputtering times of the heavy metal films are the same, and the sputtering times of the ferromagnetic metal films increase or decrease successively from a top layer to a bottom layer;
• or, the sputtering times of the heavy metal films increase successively from the top layer to the bottom layer, and the sputtering times of the ferromagnetic metal films decrease successively from the top layer to the bottom layer;
• or, the sputtering times of the heavy metal films decrease successively from the top layer to the bottom layer, and the sputtering times of the ferromagnetic metal films increase successively from the top layer to the bottom layer.