Magneto-optical spectroscopy study of the solid-state reaction in Ti/Ni multilayered films

A comparative study of the solid-state reaction (SSR) in a series of Ti/Ni multilayered films (MLF) with a bilayer period of 0.65-22.2 nm and constant Ti to Ni sublayer thickness ratio has been performed by magneto-optical (M O) spectroscopy as well as x-ray diffraction (XRD). The spectral and sublay er-thickness dependences of the MO properties of the Ti/Ni MLF were explain ed on the basis of the electromagnetic theory. A threshold nominal Ni-subla yer thickness of about 3 nm in the as-deposited Ti/Ni MLF is necessary for observing the equatorial Kerr effect. Such a fact is explained by the forma tion, by solid-state reaction, of nonmagnetic alloyed regions between pure components. The SSR in the Ti/Ni MLF caused by the low temperature annealin g leads to a formation of an amorphous Ti/Ni alloy and takes place mainly i n Ti/Ni MLF with "thick" sublayers. In the case of Ti/Ni MLF, MO turns out to be more sensitive in determining the thickness of the reacted zone, whil e XRD is more useful for the structural analysis. It was also suggested tha t the very thin nonreacted Ni sublayers have MO properties different from t he bulk. (C) 2000 American Institute of Physics. [S0021-8979(00)09517-7].