Exchange coupling of contacted ferromagnetic films: Fe on amorphous TbFe

A double layer structure consisting of Fe on amorphous Tb 20 Fe 80 has been investigated with spin-polarized photoemission as function of the thickness of the Fe film. For 40 A no exchange coupling to the underlaying TbFe is observed whereas at 30 A and less the TbFe magnetization affects significantly the magnetization of the Fe over-layer. Even for a 10-A Fe film the vast majority of the photoelectrons is shown to originate from this layer. © 1988 IEEE