MICROSTRUCTURE OF SPUTTERED EPITAXIAL NI0.80FE0.20 NIXCO1-X EXCHANGE-COUPLED BILAYERS ON ALPHA-AL2O3 (0001)/

Epitaxial Ni0.80Fe0.20/NixCo1-xO bilayers have been grown on alpha-Al2 O3 (0001) substrates by dc-sputtering. X-ray diffraction and transmiss ion electron microscopy have been employed to characterize these excha nge-coupled films. The x-ray diffraction spectrum shows only the (111) family of peaks in both Ni0.80Fe0.20 and NixCo1-xO films. Growth orie ntation relationships have been determined from diffraction patterns t aken in planar view and cross section. The relationships are: (111) Ni 0.80Fe0.20//(111) NixCo1-xO//(0001) alpha-Al2O3 and [110BAR] Ni0.80Fe0 .20 //[110BAR] NixCo1-xO//[1100BAR] alpha-Al2O3. The microstructure of these films as well as the interfacial structure between Ni0.80Fe0.20 and NixCo1-xO have been analyzed in high resolution electron microsco py and are described in this paper. In addition, the dependence of the exchange coupling field on interfacial roughness is discussed.