Magnetic Tunnel Junction Device with Improved Ferromagnetic and Free Ferromagnetic Layers

摘要

In two ferromagnetic layers that form an improved magnetic tunnel junction (MTJ) element for use in a magnetic write read head or magnetic memory storage cell of the present invention, one is "hard" or "fixed". The "ferromagnetic layer and the other one are" sensing "or" free "ferromagnetic layers, which are separated by a thin insulating tunneling layer. Each of the ferromagnetic layers is a multilayer formed from two thin ferromagnetic films that are bonded antiferromagnetically with another layer with a thin antiferromagnetic bonding film therebetween. The antiferromagnetic bonding film is selected in consideration of the composition and thickness of the material so that the magnetic moments of the two ferromagnetic films sandwiching themselves when the external magnetic field is not applied are arranged antiparallel to each other. The magnetic moments of the fixed ferromagnetic multilayer and the free ferromagnetic layer can be chosen to be arbitrarily small by having two ferromagnetic films comprising each of them substantially have the same magnetic moment. Thus, the magnetic dipole fields from each of the fixed ferromagnetic multilayer and the free ferromagnetic multilayer can be minimized, thereby reducing the magnetic interaction between the fixed ferromagnetic multilayer and the free ferromagnetic multilayer.