MAGNETORESISTANCE OF NIMNSB-BASED MULTILAYERS AND SPIN VALVES

We report magnetic and magnetoresistance (MR) measurements in the curr ent-in-plane (CIP) and current-perpendicular-to-the-plane (CPP) geomet ries of multilayers and spin-valve structures based on the predicted h alf-metallic (100% spin-polarized) ferromagnetic Heusler alloy NiMnSb. Multilayers of the form [NiMnSb/Cu]X10, as well as a trilayer spin va lve of the form [NiMnSb/Cu/Y] (Y=Ni80Fe20 and NiMnSb/FeMn) have been g rown using a low-rate, low-pressure sputtering deposition technique. T he multilayers do not show evidence of antiferromagnetic coupling betw een the NiMnSb layers, and the measured CPP magnetoresistance is 4.5% at 4.2 K. NiMnSb/Cu/NiFe spin valves and NiMnSb/Cu/NiMnSb/FeMn quasisp in-valves adopt more closely antiparallel alignments of adjacent magne tic layer magnetizations, and CPP MR ratios as high as 7.2% are measur ed at 4.2 K. Although these CPP MRs are larger than the CIP MRs for si milar samples, the largest CPP MR observed is still smaller than expec ted for a 100% spin-polarized material. (C) 1998 American Vacuum Socie ty.