Exponential behavior of the interlayer exchange coupling across non-magnetic metallic superlattices

TL;DR

This paper demonstrates that interlayer exchange coupling across non-magnetic metallic superlattices can decay exponentially with spacer thickness, contrasting the typical power-law decay, by selecting specific metals and superlattice configurations.

Contribution

It reveals the exponential decay behavior of interlayer coupling in metallic superlattices, which was previously thought to decay as a power law, and explains how to achieve this through material selection.

Findings

Coupling decays exponentially with spacer thickness N.

Exponential decay contrasts the usual N^{-2} decay.

Proper metal and superlattice design induce exponential behavior.

Abstract

It is shown that the coupling between magnetic layers separated by non-magnetic metallic superlattices can decay exponentially as a function of the spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect is due to the lack of constructive contributions to the coupling from extended states across the spacer. The exponential behavior is obtained by properly choosing the distinct metals and the superlattice unit cell composition.