Two different ferroelectric materials, Sr_0.95Ba_0.05TiO₃ and Sr_0.985Ca_0.015TiO₃, can be turned into polar metals with broken centrosymmetry via electron doping. Systematic substitution of Nb⁵⁺ for Ti⁴⁺ has revealed that these polar metals both commonly show a simple superconducting dome with a single convex shape. Interestingly, the superconducting transition temperature T_c is enhanced more strongly in these polar metals when compared with the nonpolar matrix Sr(Ti, Nb)O₃. The maximum T_c reaches 0.75 K, which is the highest reported value among the SrTiO₃-based families to date. However, the T_c enhancement is unexpectedly lower within the vicinity of the putative ferroelectric quantum critical point. The enhancement then becomes much more prominent at locations further inside the dilute carrier-density region, where the screening is less effective. These results suggest that centrosymmetry breaking, i.e., the ferroelectric nature, does not kill the superconductivity. Instead, it enhances the superconductivity directly, despite the absence of strong quantum fluctuations.

两种不同的铁电材料Sr _0.95 Ba _0.05 TiO ₃和Sr _0.985 Ca _0.015 TiO ₃通过电子掺杂可以变成中心对称性破缺的极性金属。用 Nb ⁵⁺系统替代Ti ⁴⁺表明，这些极性金属通常都显示出具有单个凸形的简单超导圆顶。_{有趣的是，与非极性基体 Sr(Ti, Nb)O 3相比}，这些极性金属的超导转变温度Tc增强得更强烈。最大Tc _{_}达到 0.75 K，这是迄今为止基于SrTiO ₃的家族中报道的最高值。然而，在假定的铁电量子临界点附近，T _{c增强出人意料地较低。}然后，在稀载流子密度区域更远的位置，屏蔽效果较差的位置，增强变得更加突出。这些结果表明，中心对称破缺，即铁电性质，不会破坏超导性。相反，它直接增强了超导性，尽管没有强烈的量子涨落。