NMR INVESTIGATION ON THE SPIN POLARIZATION OSCILLATION IN CU LAYERS OF [NI/CU] MAGNETIC SUPERLATTICES

The spatially oscillating electron spin polarization in Cu layers of [Ni/Cu] superlattice has been investigated by the nuclear magnetic resonance method. The damping exponent of the polarization oscillation deduced from line widths of Cu NMR spectra has been shown an unexpected value ''-1''. This fact reflects a topology of the Fermi surface in Cu layers. Moreover, the spectra have shown noticeable anisotropy; the spectral shape depends on the angle between the external field and the sample surfaces. From analyses of the anisotropy, we have concluded that the anisotropy originates from a change not in chi(q) of Cu layers but in the initial conditions of the oscillation determined by the interfacial conditions. From Cu-63 spin-lattice relaxation time (T1) measurements, an enhancement of the density of states at the Fermi level compared with bulk one has been found, which suggests a change in the band structure of Cu layers from the bulk one.