Interlayer coupling of magnetic multilayers across noble spacers in jellium model

Abstract

The oscillatory exchange coupling between two metal ferromagnetic layers separated by a noble metal spacer is calculated in an inhomogeneous jellium model. The one-electron Hamiltonian takes into account the kinetic energy, the electric potential due to noncompensated charge at interfaces, the exchange interaction in the Kohn-Sham approximation and the s-d interaction contribution which splits the bands in the magnetic layers. We assume that the coupling is connected with the Friedel oscillations of the electron spin density in the spacer layer. In the calculations of the coupling, we take into account the kinetic and exchange contributions of the spacer layer. These two contributions have opposite signs and their joint effect leads to a reasonable amplitude of the coupling. A dependence of the work function (the chemical potential of thin multilayers) on the thickness of the spacer layer is discussed also. The effect of the electric potential due to noncompensated charge at interfaces on the coupling is not discussed.