MOSSBAUER STUDY OF CO CU MULTILAYERS USING SN-119 PROBES

Sn-119 Mossbauer spectra of Co/Cu multilayers were studied to clarify the role of nonmagnetic layer on the magnetic coupling between ferroma gnetic layers. At 300 K, the magnetoresistance (MR) ratio of [Co(20 an gstrom)/Cu(t angstrom)] x 8 system shows a maximum value of 17% at abo ut t=23. According to Sn-119 Mossbauer spectra of [Co(20 angstrom)/Cu( 20-x angstrom)/Sn-119(1.5 angstrom)/Cu(x angstrom)] x 8 (x=0, 5 and 10 ) multilayers, a magnetic fraction is observed in every spectrum, and the ratio of the ferromagnetic fraction decreases depending on the dis tance from the Co/Cu interface. It is also observed that the polarizat ion is greatly reduced by adding Cr layer of only 2 angstrom to the Co /Cu interfaces. The spectrum of the x=10 film, measured under an exter nal field of 30 kOe, cannot be interpreted without assuming magnetic f ractions both in parallel and antiparallel to the Co magnetizations, w hich indicates an oscillation of spin polarization in a Cu layer.