Study Of Spin Waves In Ferromagnetic Bilayers With FCC Structure

On the basis of the Heisenberg exchange model, the spin-wave eigen-problem ofthe ferromagnetic bilayers with face-centered cubic structure is solved exactly at thelow temperature. The fine configuration of the two-dimensional Brillouin zone energyband with bilayers composed of same ferromagnetic films is presented and comparedwith the Puszkarski's study. The influences of interface exchange interaction on theproperty of the band structure are extensively studied. Many important conclusionsare drawn: 1) The existence type of interface modes is decided by interface exchangeinteraction constant. That is to say, there will be the optical interface modes upon thebulk modes, when the interface exchange interaction is greater than the bodyexchange interaction; on the other hand, there will be the acoustical interface modesbelow the bulk modes, when the interface exchange interaction is smaller than thebody exchange interaction. Especially, when the ferromagnetic interface exchangeinteraction is smaller than the body exchange interaction, there will be also theacoustical interface modes. Whereas this case does not appear in the simple cubicstructure. 2) The variation of interface exchange interaction constant greatlyinfluences the energy and the regions of the interface modes existing on thetwo-dimensional Brillouin zone. Furthermore, we find that the energy of the eigenmodes increases linearly with the increasing magnetic field and uniaxial anisotropy,and increased range is same.