3 research outputs found
Effect of the laser fluence on the microstructure and the relating magnetic properties of BaFe₁₂O₁₉ films grown on YSZ(111) by PLD for optimized perpendicular recording
High-quality BaFeO (BaM) films with high uniaxial anisotropy fields of H = 17.5 and 18.5 kOe were obtained by pulsed laser deposition (PLD) at two fluences of 1.5 and 5.1 J/cm on YSZ(111) substrate, using a platinum interlayer for reducing lattice mismatch. We demonstrated that the microstructure, morphology, and stoichiometry of the hexaferrite BaFeO films can be affected by raising the corresponding energy per pulse from 25 to 75 mJ. However, we also concluded that the increase of fluence leads to the formation of a non-stoichiometric BaM film through two nucleation steps and an output growth of small grains in addition to the increase of the defect density. In turn, this has contributed to the enhancement of the coercive field from H = 1769 Oe to H = 2166 Oe as it is required for the improvement of perpendicular recording resolution. We found that both the lateral coherent block size and misorientation of mosaic blocks are remarkably affected by the growth kinetics, which itself depends on the energy per pulse. For a deep understanding of the effect of laser fluence on the microstructure, chemical composition, and on the magnetic properties of thin BaM films, the results of complementary methods are combined. These methods comprise high-resolution X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy (TEM), scanning TEM combined with energy-dispersive X-ray spectroscopy, and vibrating sample magnetometer
Effect of Underlayer Quality on Microstructure, Stoichiometry, and Magnetic Properties of Hexaferrite BaFe<sub>12</sub>O<sub>19</sub> Grown on YSZ(111) by Pulsed Laser Deposition
We have studied the effect of platinum underlayer for
two deposited
thicknesses on the microstructure, crystalline quality, morphology,
chemical composition, and magnetic properties as well as magnetic
domain formation of BaFe12O19 (BaM) grown on
YSZ(111) by pulsed laser deposition (PLD). We found that PLD platinum
deposited with a thickness of 25 nm cannot withstand the dewetting
phenomenon occurring during the subsequent BaM layer growth. A smooth
and continuous Pt underlayer that possesses a sharp interface and
omits the intermixing between the BaM and substrate was successfully
achieved for a deposited Pt film thickness of 75 nm. Independent of
the thickness of the deposited Pt layer, the c-axis
orientation as well as coercivity Hc and the anisotropy HA fields were significantly improved due to a remarkable
improvement of lattice mismatch in comparison with the BaM layer grown
without a Pt underlayer on YSZ(111). By applying high-resolution X-ray
diffraction, scanning and transmission electron microscopy (SEM/TEM),
and atomically resolved scanning TEM imaging combined with energy-dispersive
X-ray spectroscopy, as well as atomic and magnetic force microscopy,
a comprehensive investigation of both structure and chemical composition
of the deposited BaM films and their interfacial regions was performed.
This study aimed to correlate the enhancement of the overall magnetic
properties and of the local spin magnetic domain orientation with
the modification of BaM microstructure and chemical composition at
the nanometer scale due to the Pt underlayer. Finally, we attempted
to understand the mechanisms that control the magnetic properties
of these BaM films in order to be able to tailor them