Enhanced superconductivity close to a non-magnetic quantum critical point in electron-doped strontium titanate
Enhanced superconductivity close to a non-magnetic quantum critical point in electron-doped strontium titanate
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DOI：
10.1038/s41467-019-08693-1
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发表时间：
2019-02
影响因子：
16.6
通讯作者：
Y. Tomioka;N. Shirakawa;K. Shibuya;I. Inoue
中科院分区：
文献类型：
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作者：
Y. Tomioka;N. Shirakawa;K. Shibuya;I. Inoue
量子临界点（QCP）的研究主要集中在磁性QCP。由于避免了临界性，已经发现了诸如超导性之类的显着现象，但我们在这里关注的是非磁性对应物，即，SrTiO_3的超导电性被认为接近于铁电QCP。在这里，我们制备了高质量的Sr 1 −xLaxTi（16 O 1 − z18 Oz）3单晶，在低温下没有局部化，这使我们能够系统地研究Sr的La替代作为引入氧空位的替代方案。基于理论模型的数据分析预测铁电QCP的出现大约在3 × 1018 cm −3左右。由于QCP，Sr 1 − xLaxTiO 3的超导圆顶可以向上升起。此外，在Sr 1 − xLaxTiO 3晶体上进行18 O交换可显著提高Tc（~ 0.6K）。这些发现提供了一个新的旋钮，观察周围的铁电QCP有趣的物理。
Studies on quantum critical points (QCP) have focused on magnetic QCPs to date. Remarkable phenomena such as superconductivity due to avoided criticality have been discovered, but we focus here on the non-magnetic counterpart, i.e., the superconductivity of SrTiO3regarded as being close to a ferroelectric QCP. Here we prepare high-quality Sr1−xLaxTi(16O1−z18Oz)3single crystals without localisation at low temperatures, which allow us to systematically investigate the La substitution of Sr as an alternative to introducing oxygen vacancies. Analysis of our data based on a theoretical model predicts an appearance of the ferroelectric QCP around 3 × 1018cm−3. Because of the QCP, the superconducting dome of Sr1−xLaxTiO3can be raised upwards. Furthermore, remarkable enhancement ofTc(~0.6 K) is achieved by18O exchange on the Sr1−xLaxTiO3crystals. These findings provide a new knob for observing intriguing physics around the ferroelectric QCP.