Formation of c-axis oriented barium ferrite thin films by alternate deposition of a Fe3O4 layer and BaO center dot 3Fe(2)O(3) layer

Deposition of c-axis perpendicularly oriented barium ferrite (BaM:BaFe12O19) thin films was attempted by means of an alternate periodic deposition of S (spinel Fe3O4) and R (BaO . 3Fe(2)O(3)) layers. The period of the layers was fixed at 1.15 nm, which corresponds to the period of hexagonal barium ferrite crystals in the c-axis direction. Films 115 nm thick were deposited on a c-axis oriented ZnO underlayer by using a dc sputtering system with three facing target sputtering sources. This layer deposition method was expected to deposit a film with much better crystallite orientation at a lower substrate temperature than needed to deposit a film when using a conventional sputter deposition method (i.e., sputter deposition using a stoichiometric BaM sintered target). The films deposited at temperatures above 540 degrees C had a hexagonal crystal structure and showed c-axis orientation, but this deposition method did not result in a marked reduction of substrate temperature needed for the deposition of a BaM film with hexagonal crystal structure. The films deposited at 650 degrees C had a clear terraced surface due to the growth of disk shaped hexagonal crystallites. The saturation magnetization of the film was about 220 emu/cc and the coercive force of the films was about 2.2 kOe. (C) 1997 American Institute of Physics.