CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

tetragonal shape, which indicates the existence of large tensile stress thin the film. This apparent
strain phenomenon will affect the internal magnetic field and thus change the resonance field.
The much smaller T1 term of 800 ˚C than those of other temperatures coincides with this strain
effect very well. Another behavior is the increasing magnetocrystalline anisotropy field (
with increasing deposition temperature, which might be attributed to the increased single crystal
quality of the as deposited thin films. The as listed spectroscopic splitting g factor (also known as
Landé g factor) has a relationship with the gyromagnetic ratio:
93
, in which and are
Bohr magneton and reduced Planck constant, respectively. The values of as calculated g factor
are slightly greater than 2, which has been also reported for experimental measurement of other
ferrite materials.[168]
Table 6. Structural and magnetic properties of nickel ferrite films deposited at different temperatures.
Structural and magnetic parameters Growth temperature (˚C)
500 600 700 800
In-plane lattice parameter a (Å) 8.354±0.002 8.346±0.002 8.348±0.003 8.366±0.001
Out-of-plane lattice parameter c (Å) 8.338±0.001 8.343±0.001 8.342±0.001 8.318±0.001
Saturation magnetization 4 MS (G) 3230 3280 3569 3757
g factor 2.24±0.003 2.27±0.01 2.28±0.009 2.28±0.03
2K1/MS (G) -75±15 -228±46 -272±38 -328±111
4 Meff (G) 2348±14 2560±46 2883±38 889±108
The line width of FMR resonance curve represents the degree of microwave loss which is
an important concern for practical microwave device application. Nickel ferrite films deposited
on MgAl2O4 at different temperatures were characterized by in plane FMR (static magnetic field
pointing at [100] direction) at microwave frequency of 9.5 GHz. The as measured thin film
thickness is in the range of (650~780 nm). As one can see in Fig.49, the FMR line width of film
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