Magnetism in rare earth-transition metal amorphous alloy films

Abstract

A number of rare earth (RE) transition metal (TM) amorphous alloy films (RE=Gd, Ho, Tb, Y; TM=Co, Fe, Ni, Mn) have been prepared across a broad compositional range by thermal evaporation. The samples were examined by polar Faraday rotation, polar Kerr rotation and magnetometer techniques. Results show that the major differences between amorphous and crystalline alloys are due to the altered state of the TM. Specifically the ordering temperature of amorphous RE‐Ni and RE‐Co alloys is higher than in the corresponding crystalline alloys, whereas the reverse is true for RE‐Fe alloys; at the same time, the TM ’’sublattice’’ magnetization is larger in the amorphous state for both Fe and Co compounds. Furthermore amorphous RE‐Mn alloys are not ordered. These facts tend to support the general concepts of the charge transfer model. Other properties such as coercivity and anisotropy are strongly dependent on the RE constituent.