You-Sheng LiNaoki KikugawaDmitry A. SokolovFabian JerzembeckAlexandra S. GibbsYoshiteru MaenoClifford W. HicksJörg SchmalianMichael NicklasAndrew P. Mackenzie2025-01-082025-01-082021-03-02https://scholars.lib.ntu.edu.tw/handle/123456789/724667A 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, ∆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 well-studied van Hove singularity. Thanks to the high precision of our measurements, these findings place stringent constraints on theories of the superconductivity of Sr2RuO4Heat capacitySuperconductivityUniaxial pressure[SDGs]SDG7journal article10.1073/pnas.2020492118