MAGNETO-OPTICAL PROPERTIES OF AMORPHOUS RE-FeCo ALLOYS

Abstract

Amorphous rare-earth transition metal alloys of composition RE1-xTMx (RE = Gd, Tb, GdTb; TM = Fe, Co, FeCo) were prepared by evaporation onto rotating glass substrates. The magnetic and magneto-optical properties have been investigated as a function of composition and temperature ranging between 4.2 K < T < TC. Also, the spectral dependence of the Kerr rotation, θK, has been measured at T = 295 K. The compositional variation of θF and θK for cobalt- and iron-based alloys reveal significant differences which can be interpreted in terms of the different concentration dependences of the Curie temperatures. The temperature dependence of θF and θK for GdFe and GdCo alloys can be described in terms of the RE and TM sublattice magnetizations inferred from the fit of the mean field theory to the measured saturation magnetizations. At low temperatures θF and θK are controlled by both the RE and TM sublattice contributions, while for high temperatures the RE contribution is significantly smaller for most alloys.