Investigation of possible giant magnetoresistance limiting mechanisms in 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 lattice 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 thicknesses below 100 Angstrom. X-ray diffraction and vibrating sample magnetometry indicated that the entire volume of the single-phase films were ferromagnetic (M-s approximate to 500 emu/cm(3)), with no evidence for a nonstoichiometric or oxidized surface layer. Hall-effect measurements and fits to resistivity versus thickness data by surface scattering models yielded mean-free-path values of 18.4 and 80-100 Angstrom, respectively. Atomic site disorder was estimated at approximate to 10% from structure factor analysis of integrated x-ray peak intensities. These results suggest that bulk properties will play the largest role in determining the effectiveness of PtMnSb in GMR applications. (C) 1997 American Institute of Physics.