High-sensitivity heat-capacity measurements on Sr2RuO4 under uniaxial pressure
High-sensitivity heat-capacity measurements on Sr2RuO4 under uniaxial pressure
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DOI：
10.1073/pnas.2020492118
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发表时间：
2021-03-09
影响因子：
11.1
通讯作者：
Mackenzie, Andrew P.
中科院分区：
文献类型：
--
作者：
Li, You-Sheng;Kikugawa, Naoki;Mackenzie, Andrew P.
关于Sr 2 RuO 4的非常规超导电性的一个关键问题仍然是序参数是单组分还是双组分。在双组分超导的假设下，单轴压力有望提升它们的简并度，导致分裂转变。对分裂跃迁最直接和最基本的探测是热容。在这里，我们报告的样品的热容量的测量受到大的和高度均匀的单轴压力。我们对任何第二次跃迁的热容特征设定了一个上限，即第一次超导跃迁热容特征的百分之几。热容量的归一化跳跃，Δ C/C，作为单轴压力的函数平稳地增长，有利于顺序参数，这些参数被允许在布里渊区的相同部分中最大化，作为研究良好的货车霍韦奇异性。由于我们测量的高精度，这些发现严格限制了Sr 2 RuO 4的超导性理论。
A key question regarding the unconventional superconductivity of Sr2RuO4 remains whether the order parameter is single- or two-component. Under a hypothesis of two-component superconductivity, uniaxial pressure is expected to lift their degeneracy, resulting in a split transition. The most direct and fundamental probe of a split transition is heat capacity. Here, we report measurement of heat capacity of samples subject to large and highly homogeneous uniaxial pressure. We place an upper limit on the heat-capacity signature of any second transition of a few percent of that of the primary superconducting transition. The normalized jump in heat capacity, Delta C/C, grows smoothly as a function of uniaxial pressure, favoring order parameters which are allowed to maximize in the same part of the Brillouin zone as the wellstudied van Hove singularity. Thanks to the high precision of our measurements, these findings place stringent constraints on theories of the superconductivity of Sr2RuO4.