Giant magnetoresistance (GMR) was known to occur in metallic bilayers
and granular materials. In 1993, GMR was also found to occur in thin f
ilms of manganates of the formula Lal(1-x)A(x)MnO(3) (A=alkaline earth
metal). Since then, there has been intense research activity relating
to the GMR of rare earth manganates and other oxides.