Abstract:
The far infrared reflectance of Sb2Te3 , Sbi.97Vo.o3Te3 and Sbi.94Cr .o6Te3 was measured near
normal incidence at different temperatures (between 45K and 300K). The direct current
resistivities of the above samples were also measured between the temperatures of 4K and
300K. Also Kramers Kronig (KK) analyses were performed on the reflectance spectra to
obtain the optical conductivities. In the doped samples, it was observed that a phonon at
62cm-1
softens to about 55cm-1 on decreasing the temperature from 295K to 45K. Also,
it was observed that the plasma frequency of the doped samples is independent of doping.
The scattering rate for the vanadium doped sample was seen to be greater than that for
the chromium doped sample despite the fact that vanadium impurity density is less than
that of chromium. The Drude-Lorentz model fits to the KK optical conductivity show
that the samples used in this work are conventional metals. Definitive measurements of
the temperature dependence of the scattering rate across the ferromagnetic transition await
equipment changes allowing measurements at low temperature using the mercury cadmium
telluride (MCT) detector.
