Pressure-induced superconductivity and phase transition in PbSe and PbTe

The Ⅳ-Ⅵ semiconducting chalcogenides are a large material family with distinct physical behavior.Here,we systematically investigate the effect of pressure on the electronic and crystal structures of PbSe and PbTe by combining high-pressure electrical transport and synchrotron x-ray diffraction(XRD) measurements.The resistivity of PbSe and PbTe changes dramatically under high pressure and a non-monotonic evolution of p(T) is observed.Both PbSe and PbTe are found to undergo semiconductor-metal transition upon compression and show superconductivity under higher pressure.The structural evolutions from the Fm■m to Pnma phase and then to the Pm■m phase in PbSe are verified by the x-ray diffraction.The present findings reveal the internal correlation between the structural evolution and the physical properties in lead chalcogenides.