  The growth and characterization of Bismuth (Bi) substituted YIG (Bi-YIG,
Bi0.1Y2.9Fe5O12) thin films are reported. Pulsed laser deposited (PLD) films
with thicknesses ranging from 20 to 150 nm were grown on Gadolinium Gallium
Garnet substrates. Two substrate orientations of (100) and (111) were
considered. The enhanced distribution of Bi3+ ions at dodecahedral site along
(111) is observed to lead to an increment in lattice constant from 12.379
angstrom in (100) to 12.415 angstrom in (111) oriented films. Atomic force
microscopy images showed decreasing roughness with increasing film thickness.
Compared to (100) grown films, (111) oriented films showed an increase in
ferromagnetic resonance linewidth and consequent increase in Gilbert damping.
The lowest Gilbert damping values are found to be (1.06) * 10E-4 for (100) and
(2.30) * 10E-4 for (111) oriented films with thickness of 150 nm. The observed
values of extrinsic linewidth, effective magnetization, and anisotropic field
are related to thickness of the films and substrate orientation. In addition,
the in-plane angular variation established four-fold symmetry for the (100)
deposited films unlike the case of (111) deposited films. This study prescribes
growth conditions for PLD grown single-crystalline Bi-YIG films towards desired
high frequency and magneto-optical device applications.
