Magneto Optic Kerr Effect (MOKE) Measurements

ID: DGC21.011.00

The above Figure shows MOKE hysteresis loops of Terfenol-D thin film on Silicon substrate at different strain levels. A four-point bending fixture is employed to strain the thin film. The change in coercivity with strain can be used to calculate the film’s magnetostriction. 

Sample Sizes:


The Magneto-Optic Kerr Effect (MOKE) describes changes to light reflected from a magnetic surface. These changes result from the off-diagonal components of the dielectric tensor. These off-diagonal components give the magneto-optic material an anisotropic permittivity, meaning that its permittivity is different in different directions. 

There are two main types of MOKE measurements. Transverse/Longitudinal MOKE to detect in-plane magnetization and Polar MOKE to detect out-of-plane magnetization.

The experimental setup consists of:

Each sample is loaded into the custom MOKE fixture.  This fixture enables the sample to be tested per ASTM standard D6272 [Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials by Four-Point Bending].  

This test results in Kerr rotation and Kerr ellipticity measured at different fields.  These measurements are used to produce a hysteresis loop. By measuring the change in M vs H loops with the applied strain one is able to calculate the coupling between magnetic and mechanical fields and estimate the magnetostriction values.  Therefore resulting in a measurement of the magnetostriction in thin magnetic film structures.  This technique can be used for the following studies