Magneto-optical Investigation of the Band Edge of CdCr2S4 and Related Absorption Measurements on Cr-doped CdIn2S4

The
⁴
T
1
and
⁴
T
2
crystal-field transitions of Cr
³⁺
have been observed in the absorption spectrum of CdIn
2
S
4
(Cr). From the similarity between the temperature dependence of the
⁴
T
2
band and the reported blue shift of the absorption edge of CdCr
2
S
4
it is concluded that in CdCr
2
S
4
this edge is caused by the
⁴
T
2
absorption band of the Cr
³⁺
ions. The polar magneto-optic Kerr effect between 560 and 700 nm and the Faraday rotation between 800 and 8000 nm are reported for CdCr
2
S
4
. The Kerr effect spectrum indicates that the intrinsic band edge of CdCr
2
S
4
is at 1.91 eV at 60°K and shifts to lower energies with decreasing temperature.