Anomalies of the refractive index and the optical energy gap of ferroelectric Pb1−xGexTe
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- Jantsch, W. Z. Physik B - Condensed Matter (1980) 40: 193. doi:10.1007/BF01294527
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The refractive index and the optical energy gap of Pb1−xGexTe (0≦x≦0.11) have been determined from transmission- and reflectivity measurements in the temperature range from 4.2 K to 300 K. At the ferroelectric phase transition a change of the temperature coefficient of both quantities is observed. A two bandk·p model calculation demonstrates a correlation of the optical energy gap with the high frequency dielectric constant. For higher values ofx (x=0.09) a splitting of absorption edge and birefringence have been observed.