TEXTURE AND SURFACE INTERFACE TOPOLOGICAL EFFECTS ON THE EXCHANGE ANDCOERCIVE FIELDS OF NIFE/NIO BILAYERS/

The texture and surface/interface topological effects on the exchange held H-ex and coercivity H-c in rf-sputtered NiO/NiFe bilayers were st udied. The NiO/NiFe bilayers with NiO crystalline textures of (111), ( 200), and (220), and different surface/interface roughness, were fabri cated by changing the sputtering conditions. The H-ex of the NiO/NiFe bilayers was inversely proportional to the thickness of NiFe. The NiO/ NiFe bilayers with different NiO textures of (111) dominant, (200) dom inant, or combinations of (111), (200), and (220), respectively, showe d almost the same dependence of H-ex on NiFe thickness. Thus, H-ex was insensitive to the texture of NiO films. The surface/interface roughn ess has a significant effect on H-c of the NiO/NiFe bilayers. By contr olling the sputtering process. NiO (45 nm)/NiFe (10 nm) bilayers with a H-ex of 39 Oe, a H-c of 4.1 Oe, and an H-ex/H-c ratio of 9.51 could be obtained. A new parameter of H-ex/H-c was introduced to describe th e exchange coupling and coercive properties in ferromagnet/antiferroma gnet coupled bilayers. A large H-ex/H-c ratio is very desirable for sp in-valve structures. (C) 1997 American Institute of Physics.