Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.
Institut für Theoretische Festkörperphysik, Karlsruher Institut für Technologie, Karlsruhe, Germany.
Nature. 2022 Jul;607(7918):276-280. doi: 10.1038/s41586-022-04820-z. Epub 2022 Jul 13.
One of the main developments in unconventional superconductivity in the past two decades has been the discovery that most unconventional superconductors form phase diagrams that also contain other strongly correlated states. Many systems of interest are therefore close to more than one instability, and tuning between the resultant ordered phases is the subject of intense research. In recent years, uniaxial pressure applied using piezoelectric-based devices has been shown to be a particularly versatile new method of tuning, leading to experiments that have advanced our understanding of the fascinating unconventional superconductor SrRuO (refs. ). Here we map out its phase diagram using high-precision measurements of the elastocaloric effect in what we believe to be the first such study including both the normal and the superconducting states. We observe a strong entropy quench on entering the superconducting state, in excellent agreement with a model calculation for pairing at the Van Hove point, and obtain a quantitative estimate of the entropy change associated with entry to a magnetic state that is observed in proximity to the superconductivity. The phase diagram is intriguing both for its similarity to those seen in other families of unconventional superconductors and for extra features unique, so far, to SrRuO.
在过去二十年中，非常规超导领域的主要发展之一是发现大多数非常规超导体形成的相图还包含其他强关联态。因此，许多人们感兴趣的系统接近不止一种不稳定性，而在产生的有序相中进行调谐是一项激烈研究的主题。近年来，使用基于压电的设备施加的单轴压力已被证明是一种特别通用的新调谐方法，导致了实验，从而增进了我们对迷人的非常规超导体 SrRuO（参考文献）的理解。在这里，我们使用我们认为是首次包括正常态和超导态的弹性焓效应的高精度测量来绘制其相图。我们观察到在进入超导态时熵急剧下降，与范霍夫点的配对模型计算非常吻合，并获得了与在超导附近观察到的磁态进入相关的熵变化的定量估计。该相图不仅与在其他非常规超导家族中看到的相图相似，而且还具有迄今为止 SrRuO 所特有的额外特征，这很有趣。
