The physical origin of MOKE is the magnetic circular dichroism effect: exchange and spin-orbit coupling in a magnetic material lead to different absorption spectra for left- and right-circularly polarized light.Measuring the change of the polarization of the reßected beam (often referred to as Kerr angle ΘKerr) gives access to the magnetization state of the sample.
With MOKE it is possible to study quasi-static magnetization reversal properties and magnetic anisotropies. When using a pulsed laser system it is also possible to study the time dependence of the magnetization under the influence of, e.g., a pulsed magnetic field or a microwave field. Since it is an optical technique it is non invasive, and the spatial resolution is only limited by the optical resolution. Thus, we are able to study the static and dynamic properties of magnetic thin films and magnetic structures with lateral dimension down to 1 μm.