Ruderman–Kittel coupling between ferromagnets separated by a nonmagnetic layer

Abstract

For the coupling of two ferromagnets separated by a nonmagnetic layer, the Ruderman–Kittel [C. Kittel, Quantum Theory of Solids (Wiley, New York, 1963)] theory gives an expression which oscillates as a function of the thickness of the laser and asymptotically decreases as the reciprocal square of the thickness. The prefactor is independent of the electron density.