Magneto-Optical Effects of Tetrahedrally Coordinated Co2+ in Ferrites II: Effects of Low Symmetry Crystal Field S4 on Faraday Rotation Spectrum.

The effect of the low-symmetry crystal field S
₄
on the spectral shape of Faraday rotation in ferrites containing tetrahedral Co
²⁺
ions was investigated. The calculated shape of Faraday rotation in
⁴
T
₁
(
⁴
F) becomes broad with increasing a', a parameter proportional to the magnitude of the S
4
low-symmetry field, above about a' = 1000cm
^-1
and has a shoulder or other structure when a' ~ 2000 cm
^-1
. Using the value a' = 2000 cm
^-1
, it is possible to explain satisfactorily the broad shape of the experimentally observed Faraday rotation at about 1.5 μm in a (Y
_2.8
Gd
_0.2
)(Fe
_4.6
Co
_0.2
Ge
_0.2
)O
₁₂
thin film grown by the conventional liquid phase epitaxy (LPE) method.