Anomalous resistivity near the ferroelectric phase transition in (Pb, Ge, Sn)Te alloy semiconductors

The phase transition in ${\mathrm{Pb}}_{1-x}{\mathrm{Ge}}_x\mathrm{Te}$ ($0<x<\mathrm{}0.10\mathrm{}$) and ${\mathrm{Pb}}_{1-x}{\mathrm{Sn}}_x\mathrm{Te}$ has been systematically investigated by the electrical-transport method. The composition dependence of the transition temperature in ${\mathrm{Pb}}_{1-x}{\mathrm{Ge}}_x\mathrm{Te}$ determined from an electrical resistivity anomaly is in good agreement with other experiments. We found that the resistivity-anomaly peak position increases with a reduction of the anomaly under a strong magnetic field in ${\mathrm{Pb}}_{1-x}{\mathrm{Ge}}_x\mathrm{Te}$ ($x=0.01,0.015\mathrm{}$) and ${\mathrm{Pb}}_{1-x}{\mathrm{Sn}}_x\mathrm{Te}$ ($x=0.40\mathrm{}$). The magnetic field dependence is tentatively explained by an interband-electron—TO-phonon coupling model, taking into account the phonon anharmonicity.