Theoretical approach to the Curie temperature shift in FM1/NM/FM2/SUB (ferromagnetic metal 1/nonmagnetic metal/ferromagnetic metal 2/substrate) systems

An itinerant-electron model is proposed for investigating the Curie temperature shift in indirectly coupled itinerant ferromagnetic metal/nonmagnetic metal/ferromagnetic metal (FM2)/substrate structures. The Coulomb correlation between the electrons in the ferromagnetic metal is treated by using the spectral density approach. The magnetic susceptibility is used to determine the Curie temperature shift due to the interlayer exchange coupling. The relation between the Curie temperature shift and the interlayer exchange coupling is studied. It shows that the Curie temperature shift is related to the strength of the interlayer exchange coupling due to FM2 sublayers other than that of the whole system at high temperature. Good agreements with experiments are obtained.

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