Direct evidence of spin polarization oscillations in the Cu layers of Fe/Cu multilayers observed by NMR

Evidence of the existence and distribution of an induced spin polarization of the conduction electrons in the Cu layers of Fe/Cu multilayers has been obtained by nuclear magnetic-resonance (NMR). Fine structure associated with the spin-echo signal of ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$ nuclei shows that the spin polarization and an associated exchange field oscillate in sign, similar to the characteristics of the RKKY interaction. However, an accurate determination of the period of the oscillations cannot be determined solely from the NMR data at the present time.