Superconductivity of Degenerate Semiconductors

Some semimetals or heavily doped semiconductors (carrier densities in excess of 10 cm ) were first shown to be superconducting by Hein and his associates (GeTe, SnTe). Subsequently, non-stoichiometric and doped SrTi03 were also shown to be superconducting. The compound SrTiOa is ferroelectric and highly polar. 

Although 7 for these materials is very low ( 1°K and less), these materials are of theoretical interest because their superconducting behavior can be studied over a wide range of carrier concentration [and therefore iV(0)]. 

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