INTERDIFFUSION IN A TB-VERTICAL-BAR-Y SUPERLATTICE - AN EXPLORATORY NUCLEAR-MAGNETIC-RESONANCE STUDY

We have carried out an exploratory NMR study of interdiffusion at inte rfaces between epitaxially grown laminae of rare-earth metals. The sys tem investigated was a terbium-yttrium superlattice grown by molecular -beam epitaxy at similar to 270 degrees C. The NMR spectrum of Tb-159 shows satellites associated with Tb ions with different numbers of Y n eighbours and therefore provides information about the yttrium concent ration profile resulting from interdiffusion. Our data are interpreted in terms of a model based on thermally activated diffusion and which allows for the progressive decrease in sigma, the RMS diffusion length , from the lowest to the highest interface. The diffusion coefficient, provisionally assumed to be independent of composition, is found to b e (9.0 +/- 0.6) x 10(-23) m(2) s(-1) at the growth temperature.