论文标题
SR $ _2 $ ruo $ _4 $在平面内压力下的上限关键领域
Upper Critical Field of Sr$_2$RuO$_4$ under In-Plane Uniaxial Pressure
论文作者
论文摘要
已经证明，单轴内压力在状态密度下接近LIFSHITZ过渡和相关的Van Hove奇异性（VHS），可以强烈调整SR2RUO4的超导状态。在VHS上，$ T_C $和平面外和临界场的临界场均得到强烈增强，后者随着温度从凸变为凹面而改变了其曲率。然而，由于菌株不均匀性，到目前为止无法确定上部临界场如何随应变而变化。在这里，我们显示了两个上临界场的应变依赖性，这是由于样品制备的改进而实现的。我们发现平面上的上限临界场主要在$ t_c $中是线性的。另一方面，平面外临界场在$ t_c $中的功率较高，并且在VHS上达到峰值。 $ h_ \ mathrm {c2 || c} $的强度增加和形式的变化非常接近范霍夫菌株，并指出了在LifShitz Transition的状态密度和间隙幅度的强烈增强。
In-plane uniaxial pressure has been shown to strongly tune the superconducting state of Sr2RuO4 by approaching a Lifshitz transition and associated Van Hove singularity (VHS) in the density of states. At the VHS, $T_c$ and the in- and out-of-plane upper critical fields are all strongly enhanced, and the latter has changed its curvature as a function of temperature from convex to concave. However, due to strain inhomogeneity it has not been possible so far to determine how the upper critical fields change with strain. Here, we show the strain dependence of both upper critical fields, which was achieved due to an improved sample preparation. We find that the in-plane upper critical field is mostly linear in $T_c$. On the other hand, the out-of-plane upper critical field varies with a higher power in $T_c$, and peaks strongly at the VHS. The strong increase in magnitude and the change in form of $H_\mathrm{c2||c}$ occur very close to the Van Hove strain, and points to a strong enhancement of both the density of states and the gap magnitude at the Lifshitz transition.
