PHONON AND SPIN-WAVE SPECTRA STUDY ON IN-SITU OXIDIZING SPUTTERED NI NIO MULTILAYERS/

An improved sputtering method, which is named ''in situ oxidizing sput tering'' was used to prepare periodic Ni/NiO multilayers. Samples stud ied in this letter contains 20 pairs of Ni/NiO with period about 100 A ngstrom. In Raman scattering, the low frequency phonon modes are inter preted as LA phonon folding effect, which is usually measured in super lattices with a strict periodic structure. The ferromagnetic resonance spectra were also recorded at room temperature with microwave frequen cy 9.777 GHz. The analysis of spin wave resonance indicates that Ni su blayers are coupled with each other, which is the mechanism that surel y relates to the amorphous-like NiO spacers.