Exchange coupling of NiO CoFeB films

The exchange coupling in NiO/CoFeB films was investigated. A unidirectional anisotropy was obtained in films with NiO layer thickness of 30-50 nm. The crystal texture of films and magnetic properties were found to be differen t when the stacking sequence was reversed. In glass/Cu/CoFeB/NiO films, a s trong NiO(111) peak was observed with increasing NiO thickness and the exch ange coupling field was about 30 Oe. On the other hand, in the reversed gla ss/NiO/CoFeB/Cu films, the intensity of the NiO (111) peak was much weaker and the exchange coupling field was about 60 Oe. A drastic increase in the coercivity was also observed. (C) 1999 Elsevier Science B.V. All rights res erved.