Magnetooptical response of permalloy multilayer structures on different substrate in the IR–VIS–UV spectral range

The magnetooptical (MO) response of Ru/Py/Ta thin film stacks with 4, 8, and 17 nm thick Ni 81 Fe 19 permalloy (Py) films on a SiO 2 /Si and a ZnO substrate was measured by vector magnetooptical generalized ellipsometry. The MO response from VMOGE was modelled using a 4  ×  4 Mueller matrix algorithm. The wavelength-dependent, substrate-independent and thickness-independent complex MO coupling constant ( Q ) of Py in the Ru/Py/Ta thin film stacks was extracted by fitting Mueller matrix difference spectra in the spectral range from 300 nm to 1000 nm. Although the composition-dependent saturation magnetization of Ni x Fe 1− x alloys ( x   =  0.0…1.0), e.g. of Ni 81 Fe 19 , is predictable from the two saturation magnetization end points, the MO coupling constant of Ni x Fe 1− x is not predictable from the two Q end points. However, in a small alloy range (0.0  <   x   <  0.2 and 0.8  <   x   <  1.0) the composition-dependent Q of Ni x Fe 1− x can be interpolated from a sufficiently high number of analyzed Ni x Fe 1− x alloys. The available complex MO coupling constants of six different Ni x Fe 1− x ( x   =  1.0 to 0.0) alloys were used to interpolate MO response of binary Ni x Fe 1− x alloys in the range from x   =  0.0 to x   =  1.0.