论文标题
Sr $ _ {0.95} $ ba $ _ {0.05} $ tio $ _3 $和sr $ _ {0.985} $ ca $ _ {0.015} $ tio $ _3 $ _3 $ _3
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
论文作者
论文摘要
两种不同的铁电材料，Sr $ _ {0.95} $ ba $ _ {0.05} $ tio $ $ _3 $和SR $ _ {0.985} $ ca $ _ {0.015} $ _ {0.015} $ tio $ _3 $，可以将中心质量损坏的金属变成电气中的极性金属。对于Ti $^{4+} $的NB $^{5+} $的系统替换表明，这些极性金属通常显示出具有单个凸形形状的简单超导圆顶。有趣的是，与非极性矩阵SR（TI，NB）O $ _3 $相比，这些极性金属的超导过渡温度$ T_ \ MATHRM {C} $在这些极性金属中的增强更强。最大$ t_ \ mathrm {C} $达到0.75K，这是迄今为止基于SRTIO $ _3 $的家庭中报告的最高值。但是，在推定的铁电量子关键点附近，$ t_ \ mathrm {c} $增强率出乎意料地降低。然后，在稀释载体密度区域内进一步的位置上，增强功能变得更加突出，在该区域内筛选效率较低。这些结果表明，中心对称性破裂，即铁电性质，不会杀死超导性。取而代之的是，尽管没有强大的量子波动，但它仍直接增强了超导率。
Two different ferroelectric materials, Sr$_{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 doping. Systematic substitution of Nb$^{5+}$ for Ti$^{4+}$ has revealed that these polar metals both commonly show a simple superconducting dome with a single convex shape. Interestingly, the superconducting transition temperature $T_\mathrm{c}$ is enhanced more strongly in these polar metals when compared with the nonpolar matrix Sr(Ti,Nb)O$_3$. The maximum $T_\mathrm{c}$ reaches 0.75K, which is the highest reported value among the SrTiO$_3$-based families to date. However, the $T_\mathrm{c}$ 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.
