ENHANCED MAGNETORESISTANCE IN ANNEALED AND CR DOPED FE CR MULTILAYERS/

In previous work we reported that the magnetoresistance of Fe/Cr multi layers can be increased by annealing the films at moderate temperature s, which increases the spin-dependent scattering of the conduction ele ctrons. Here we present Mossbauer data that demonstrate that the struc tural effect of annealing is to promote Cr interdiffusion into the bul k of the iron layers rather than short scale intermixing at the interf aces. We have also investigated the effect of increasing the asymmetri c scattering by adding chromium to the iron in Fe/Cr multilayers. The additional Cr was either alloyed with the Fe in compositions ranging f rom 1.5% to 50% Cr in Fe, or concentrated into 1 or 2 Angstrom layers embedded at various positions in the Fe. We report enhanced room-tempe rature magnetoresistance of up to 11.4% in sputter-deposited Fe/Cr mul tilayers when the Fe layers are doped with 20% Cr. The maximum magneto resistance observed for samples with embedded Cr layers was 10.5%. In comparison, the magnetoresistance was 7.5% in a similar, undoped sampl e. (C) 1996 American Institute of Physics.