Praeseodymium -123: 30 Years Later\textellipsis Why Isn't It Superconducting\textellipsis or Even Conducting?

The years 1986-87 witnessed the explosion of the discovery of the rare earth copper oxide perovskite family of high temperature superconductors. Alone of those with the single phase RE-123 stoichiometry that remained non-superconducting\textellipsis or even conducting \textellipsis at all temperatures down to 0.4 K was Pr-123.$^{\mathrm{1}}$ Today, this finding remains one of the principal mysteries of the HTSC family of compounds. We revisit this continuing conundrum from the perspective of today, 30 years later, and explore various quantum models which might clarify this issue, as well as propose possible applications of Pr-123 films to embody Landauer-Buttiger ballistic-controlled ``smart'' gates in future MOSFET devices.$^{\mathrm{2\thinspace }}$ \newline $^{\mathrm{1}}$ M.E. Lopez-Morales, et al., Physical Review B 41, 6655 (1990). \underline {http://w2agz.com/Publications/Science{\%}20{\&}{\%}20Technology/IBM/72{\%}20(1990){\%}20Role{\%}20of{\%}20Oxygen{\%}20in{\%}20PrBa\textunderscore 2Cu\textunderscore 3O\textunderscore 7-y{\%}20-{\%}20Effect{\%}20on{\%}20Structural{\%}20and{\%}20Physical{\%}20Properties.pdf} \newline $^{\mathrm{2}}$ P.M. Grant, Possible Quantum Transport in Pr-123 Perovskites, 2012 Meeting of the Cal-Nev Section of the APS. \underline {http://w2agz.com/Presentations/2012/11-02{\%}20Cal-Nev-APS{\%}20San{\%}20Luis{\%}20Obispo/Cal\textunderscore Poly\textunderscore Talk-Static.pdf}