National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8565, Japan.
Nat Commun. 2019 Feb 13;10(1):738. doi: 10.1038/s41467-019-08693-1.
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 SrTiO regarded as being close to a ferroelectric QCP. Here we prepare high-quality SrLaTi(OO) single 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 × 10 cm. Because of the QCP, the superconducting dome of SrLaTiO can be raised upwards. Furthermore, remarkable enhancement of T (~0.6 K) is achieved by O exchange on the SrLaTiO crystals. These findings provide a new knob for observing intriguing physics around the ferroelectric QCP.
迄今为止，对量子临界点（QCP）的研究主要集中在磁性 QCP 上。已经发现了一些引人注目的现象，例如由于临界回避而产生的超导性，但我们这里关注的是非磁性的对应物，即被认为接近铁电 QCP 的 SrTiO 的超导性。在这里，我们在低温下制备了没有局部化的高质量 SrLaTi(OO)单晶，这使我们能够系统地研究 Sr 的 La 取代作为引入氧空位的替代方法。基于理论模型对我们数据的分析预测，铁电 QCP 大约出现在 3×10^-3 cm 处。由于 QCP，SrLaTiO 的超导穹顶可以向上提升。此外，在 SrLaTiO 晶体上进行 O 交换可使 T 值显著提高（约 0.6 K）。这些发现为观察铁电 QCP 周围有趣的物理现象提供了一个新的旋钮。
