Monitoring magnetic properties with light
We use the magneto-optical Kerr effect (MOKE) to
assess the magnetization behavior of our electrodeposited samples. In this
non-destructive surface sensitive technique, polarization-modulated laser
light reflects from a magnetic surface (our sample) in the presence of
a sweeping magnetic field. Since light is an electromagnetic field,
it's not surprising that the magnetic field of the sample interacts with
the light to cause a very slight change in the light's polarization and
ellipticity. We measure these changes in the light as an intensity change
through nearly-crossed polarizers, recording the intensity as a function
of the applied magnetic field.
The longitudinal Kerr effect, which we measure using
a configuration like the one shown above, yields qualitative information
regarding alignment of magnetic moments in the surface plane of the sample.
To measure the magnetization component perpendicular to the sample surface,
the experimental configuration must be modified so that the applied magnetic
field is perpendicular to the sample.
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on May 21, 2003.