High sensitivity heat capacity measurements on Sr2RuO4 under uniaxial pressure
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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 development of new high-frequency methodology for 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 per cent of the primary superconducting transition. The normalized jump in heat capacity, Δ C/C, grows smoothly as a function of uniaxial pressure, but we find no qualitative evidence of a pressure-induced order parameter transition. Thanks to the high precision of our measurements, these findings place stringent constraints on theories of the superconductivity of Sr2RuO4.
Li , Y -S , Kikugawa , N , Sokolov , D A , Jerzembeck , F , Gibbs , A S , Maeno , Y , Hicks , C W , Schmalian , J , Nicklas , M & Mackenzie , A P 2021 , ' High sensitivity heat capacity measurements on Sr 2 RuO 4 under uniaxial pressure ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 118 , no. 10 , e2020492118 . https://doi.org/10.1073/pnas.2020492118
Proceedings of the National Academy of Sciences of the United States of America
Copyright © 2021 the Author(s). This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1073/pnas.2020492118.
DescriptionFunding: Parts of this work were funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - TRR 288 -422213477 (projects A10 and B01). NK acknowledges the support from JSPS KAKENHI (nos. JP17H06136 and JP18K04715) and JST-Mirai Program (no. JPMJMI18A3) in Japan and YM from JSPS KAKENHI (nos. JP15H05852, JP15K21717) and JSPS core-to-core programme. YSL acknowledges the support of a St Leonard’s scholarship from the University of St Andrews, the Engineering and Physical Sciences Research Council via the Scottish Condensed Matter Centre for Doctoral Training under grant EP/G03673X/1, and the Max Planck Society.
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