Superconductivity enhancement in polar metal regions of Sr${}_{0.95}$Ba${}_{0.05}$TiO${}_3$ and Sr${}_{0.985}$Ca${}_{0.015}$TiO${}_3$ revealed by the systematic Nb doping

Yasuhide Tomioka, Naoki Shirakawa, Isao H. Inoue

Two different ferroelectric materials, Sr${}_{0.95}$Ba${}_{0.05}$TiO${}_3$ and Sr${}_{0.985}$Ca${}_{0.015}$TiO${}_3$, can be turned into polar metals with broken centrosymmetry via electron do…