Magneto-Optical Kerr Effect (MOKE) spectrometer:

Magneto-Optical Kerr Effect resides in the change of the polarization state of the light after reflection on a magnetic material (Fig. 1). The polarization state of the light is also changed when transmitted through a magnetic transparent sample, phenomenon that is called Faraday Effect.

Fig. 1. Principle of the Kerr and Faraday effects

A change in magnetic field strength and direction causes a change in refractive index of the material. Therefore MOKE can be used to record magnetization hysteresis loops from ferromagnetic films.

Our home-made set-up works in the polar geometry, i.e. the light beam is quasi-normally incident on the sample surface. This geometry is sensitive to sample magnetization parallel to the sample surface normal.

Fig. 2. MOKE - Set-up: 1 - Light source 2 - Concave mirror 3 - Plane mirror 4 - Polarizer 5 - Photoelastic modulator (PEM) 6 - Polarization Analyzer 7 - Concave mirror 8 - Monochromator 9 - Photomultiplier The white line indicates the light path through the set-up.