GIANT MAGNETORESISTANCE EFFECTS IN INTERMETALLIC COMPOUNDS (INVITED)

Giant magnetoresistance (GMR) effects are observed in several classes of bulk magnetic materials. The resistance changes at metamagnetic tra nsitions connected with reorientation of 4f moments are only moderate due to the relatively weak coupling of the 4f and conduction electrons . Much larger GMR effects can be achieved by mechanisms involving the d states (RhFe, RCo(2)), though the most spectacular resistance variat ions are connected with metamagnetic transitions in U-intermetallic an tiferromagnets. This phenomenon can be interpreted as due to Fermi sur face gapping (due to magnetic superzones) and/or due to spin-dependent scattering in analogy with magnetic multilayers.