There are two varying forms of the Kerr effect which are the electro optic Kerr effect and then there is the optical Kerr effect. The electro optic Kerr effect is one in which a varying DC field is applied. The MOKE as studied will consider the Kerr effect in which light itself is considered. Where the electro optic effect is such that the DC current is applied to the non-linear optic medium for the perturbation of refractive index of material, in the case of the light-based effect it so happens that the material itself could act as a wave plate here. Optical Kerr is amore of a self-induced effect hence where the light creates the force field. Now in the case of the Kerr effect, there are many off diagonal components observed at this point that would induce magneto anisotropic permittivity. Permittivity is hence allowed in different directions, in the speed of light, as given by the equation.
Where the variables for velocity of light through medium Vp, the magnetic permeability, and the material permittivity are given. Speed of light will vary based on the orientation and hence there will be many fluctuations in the context of polarization.
Now the MOKE effect states that the plane of polarization of the light gets rotated when the light reflection is observed from a magnetic material. Physical origin of MOKE lies in this circular effect. There is a form of exchange and spin-orbit coupling observed at this point. This leads to different forms of absorption spectra. Especially in the context of the left circular and the right circular polarized light, it is observed that there are absorption spectra created. The measurement of these changes in polarization leads to the reflected beam, and the angle of this reflected beam are called the Kerr angle. The Kerr angle is what gives access to magnetization state in the sample so that it could be analyzed. The MOKE has been used popularly for the study of quasi-static magnetization reversal property studies and more. It has been used in conjunction with the pulsed laser system and the dependence in magnetization characteristic is assessed thus. It is equally possible to study for effects such as frequency and more.
The MOKE is a popular technique because of how it is non-invasive. It is carried out under the influence of a pulsed magnetic field and sometimes a microwave field and both are critically non-invasive except for some material interactions. In the context of static or thin magnetic films, there is a need for noninvasive techniques and the MOKE comes handy here. Spatial resolutions are good with the MOKE and the spatial resolutions are only limited by the optical resolution that is used at this point. In the context of understanding stating and dynamic properties of thin magnetized films, one more aspect to be understood is that the lower the lateral dimension the less the resolution that can be applied for understanding sample. However, MOKE restricts resolution and capability only so far as the optical resolution and this increases efficiency in assessment. Static and dynamic natures of the thin magnetic films can hence be studied in a much more effective manner.