Surface optical and magneto-optical properties of as-quenched (AQ)
Co<sub>66</sub>Fe<sub>4</sub>Si<sub>15</sub>B<sub>15</sub> amorphous ribbons are studied using
the magneto-optic vector magnetometry. Both in-plane magnetization components (longitudinal M<sub>L</sub> and transversal M<sub>T</sub>)
detect typical uniaxial magnetic anisotropy with the easy axis close to the ribbon axis. Moreover, the total magnetization
vector |M|/M<sub>S</sub> = (M<sub>L</sub><sup>2</sup>)+
M<sub>r</sub><sup>2</sup>)<sup>0.5</sup>/M<sub>S</sub> indicates that coherent rotation of magnetization dominates. In the regions, where |M|/MS < 1, we observe the magnetic domains using the Kerr optical microscope. The fact that domain structure closely
relates with the magnetic anisotropy is confirmed. Surface optical (refractive index) and magneto-optical (the Voight
constant) properties of AQ ribbon are obtained by comparing the measured magneto-optical Kerr angles at different
incident angles with the theoretical model based on the light propagation in layered anisotropic media.
FeNbB amorphous ribbons are promising soft magnetic materials with adjustable surface magnetic properties.
Field-annealing is applied to control nano-crystallized surface magnetic films, which can be monitored
by using magneto-optical techniques. In this paper we analyze depth sensitivity of magneto-optic methods
and investigate the surface magnetic properties of amorphous ribbons. Magneto-optic response and depth
sensitivity is modeled using 4 x 4 matrix formalism of light propagation in anisotropic multilayers. Optical
and magneto-optical properties of near surface nano-crystallized phases differ from those of deeper bulk
material. The complex longitudinal magneto-optic Kerr effect is measured for <i>s</i>- and <i>p</i>-polarized incident
light. Both magneto-optical angles: the Kerr rotation and Kerr ellipticity are analyzed. Separation of
magneto-optic contributions from different layers is obtained using different phase sensitive and penetration
depth of the complex magneto-optic measurements. For these measurements we use magneto-optic vector
magnetometry based on differential intensity between two polarization states.