INVESTIGATION OF POSSIBLE GIANT MAGNETORESISTANCE LIMITING MECHANISMSIN EPITAXIAL PTMNSB THIN-FILMS

To investigate the possibility of using the half-metallic ferromagnet PtMnSb in giant magnetoresistance (GMR) applications, we have examined the surface roughness, structural uniformity, mean-free path, and lat tice disorder of sputtered epitaxial PtMnSb(111) films on Al2O3(0001) in the range 85 Angstrom less than or equal to t less than or equal to 1100 Angstrom. Atomic force microscopy revealed the films to be very flat, with an rms roughness of approximate to 3 Angstrom for thickness es below 100 Angstrom. X-ray diffraction and vibrating sample magnetom etry indicated that the entire volume of the single-phase films were f erromagnetic (M-s approximate to 500 emu/cm(3)), with no evidence for a nonstoichiometric or oxidized surface layer. Hall-effect measurement s and fits to resistivity versus thickness data by surface scattering models yielded mean-free-path values of 18.4 and 80-100 Angstrom, resp ectively. Atomic site disorder was estimated at approximate to 10% fro m structure factor analysis of integrated x-ray peak intensities. Thes e results suggest that bulk properties will play the largest role in d etermining the effectiveness of PtMnSb in GMR applications. (C) 1997 A merican Institute of Physics.