Magneto-Optic Kerr Effect

Electronic & Chemical & Magnetic Characterization (Magnetic characterisation)

When linearly polarized light is reflected from a magnetic film, its polarization becomes elliptic (Kerr ellipticity) and the polarization principal axis is rotated (Kerr rotation). This rotation is proportional to a component (depending on the geometry of experiment) of the magnetization of the film. For this reason the MOKE magnetometry is a very popular tool for the characterization of the magnetic properties of materials.

Since the laser spot can be focused down to a few microns, the magnetic properties (e.g. coercivity, squareness ratio) of single micrometer or submicrometer structures can be evaluated. With a suitable set-up the sensitivity of the MOKE apparatus can be pushed to detect the signal coming from very thin films (ideally down to the atomic plane) making the technique suitable for the study of magnetic structure of thin films, interfaces and nanostructures.

Note that although this technique can be very sensitive, no quantitative measure of the magnetization is provided. Nevertheless, from the shape of the hysteresis loop, both static and dynamic magnetization reversal processes can be investigated in detail. Longitudinal and polar configurations are used routinely to detect the in-plane or the out-of-plane magnetization components, respectively. This technique is well suited to characterize either flat or micron- and submicron-patterned films.

          provided at NFFA-Europe laboratories by:
          provided by:
Magneto-Optical Kerr effect @ Surface and Nano Science Lab
Transversal, polar and 3D MOKE measurements
Diode laser: 635nm, 5mW
Glan-Thompson prism polarizer and analyzer (if necessary) GaAsP photodiode
Magnetic field: (max) transversal MOKE 600 Oe, polar MOKE 300 Oe, 3D MOKE 80 Oe
Laser spot size: 100μm
T range: 200 K – 650 K
Experimental chamber connected to atomic resolution STM, ARPES (beamline APE-Low Energy), XAS (beamline APE-High Energy)
Surface magneto-optic Kerr effect magnetometer
Measurements of hysteresis loops in the longitudinal configuration for films, multilayers and patterend structures
5mW laser source
200 microns
Room temperature Maximum longitidinal field of 0.25 T
XYZ sample scanning stage
Maximu sample dimensions 2x2 cm^2