MO Kerr effects

Figure 7.6. MO Kerr effects taking piace when light is reflected from the surface of a magnetized material polar (a), longitudinal (b), and transverse (c) effects.

MO Kerr effects are used to observe the domain structure of opaque materials. If the magnetization vector is perpendicular to the sample plane, then the polar Kerr effect is utilized. If the magnetization lies in the sample plane, then structure images can be obtained either in the longitudinal geometry with polarizers or in the transverse geometry without polarizers. 

Figure 7.3 Schematic of the PLD system recently installed by CNR-SPIN within the NFFA-demonstrator project at the APE beamline of Elettra synchrotron (Italy). The system allows in situ sample characterization, including magneto-optic (MO) Kerr effect, low energy electron diffraction (LEED), and Auger...

From the write and read process sketched so far, some requirements for MO media can be derived (/) a high perpendicular, uniaxial magnetic anisotropy K in order to enable readout with the polar Kerr effect (2) a magnetoopticady active layer with a sufficient figure of merit R 0- where R is the reflectivity and the Kerr angle (T) a Curie temperature between 400 and 600 K, the lower limit to enable stable domains at room temperature and the upper limit because of the limited laser power for writing. 

The character of the dependence of K on x greatly depends on the angle formed by the monomer dipole mo (rigidly bonded to the chain) and the chain direction. The parallel component of this dipole provides a positive (corresponding to the sign of Aa) contribution to the Kerr effect. It is determined by the first term in Eq. (97) or (100). The normal component of the monomer dipole mq si" 6 yields a negative (opposite to the sign of Aa) contribution to EB (second term in Eqs. (97) and (100)). 

The polar and longitudinal Kerr effects constitute the group of longitudinal MO effects. Under certain conditions, variations of the intensity of linearly polarized reflected light are observed in the configuration of either the polar or longitudinal Kerr effect geometry [30]. 

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