  Barium hexaferrite (BaFe12O19 or BaM) films were grown on c-plane sapphire
(0001) substrates by pulsed laser deposition (PLD) to evaluate the effects of
the laser fluence on their composition, structure, and magnetic properties.
Continuum's Surelite pulsed 266nm Nd:YAG laser was employed, and the laser
fluence varied systemically between 1 and 5.7 [J/cm2]. Deviations from the
stoichiometric transfer between the BaM targets and deposited thin films
occurred as the laser fluence changed. The Fe to Ba ratio in the films
increased with the laser fluence. The films deposited at the laser fluences
below 4 J/cm2 showed undesirable 3-dimensional islands on the surface.
Moreover, insufficient laser energy resulted in the deposition of some
secondary phases, for example, barium monoferrite (BaFe2O4) and Magnetite
(Fe3O4). On the other hand, laser fluences above 5 J/cm2 promoted resputtering
and degraded the film quality, structure, and magnetic properties. BaM films
deposited at 4.8 J/cm2 - the optimal laser fluence - showed excellent c-axis
orientation perpendicular to the film plane with the anisotropy field of 16 kOe
and saturation magnetization of 4.39 kOe. These results clearly demonstrate a
strong influence of the laser parameters on the PLD-grown hexaferrite films and
pave the path for the high-yield production using PLD systems.
