Thin Film Magnetization Analysis

A "Graphical Method" is used for analysis of the magnetization direction in terms of the magnetic energy, and for prediction of the hysteresis loop shape of ferromagnetic thin films. Three major magnetization conditions are discussed: 1) condition of magnetization with an 180° field applied: 2) condition of magnetization with a 90° field applied; and 3) condition of magnetization with both the 90° and the 180° field applied. Corresponding to these magnetization conditions, the hysteresis loop shapes are predicted and constructed showing close identity to those experimentally observed. These conditions are chosen because of their importance to computer applications. In the graphical method, the principle of superposition applies. Using this method, the magnetic energy relationships are readily established. The general expression for the total free energy equation is: Et = Ek+E¿+EH¿ where Ek is the anisotropy energy, E¿ is the magnetostriction energy, and EH¿ is the magnetization energy. Since the method of construction of the total free energy curve as well as the hysteresis loop is simple and mechanical, a quite complex magnetization condition with a multiplicity of fields of different magnitudes and directions may be simplified and handled by graphical means with ease. Thus, the present scheme should be a practical and useful tool for analysis and engineering design of magnetic devices and systems utilizing ferromagnetic thin films.