利用弹热效应测量单轴压力下的熵映射
Entropy mapping under uniaxial pressure utilizing the elastocaloric effect
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中文总结 AI 辅助
本研究开发交流弹热效应测量框架，应用于Sr₂RuO₄获得相图熵映射，推导其绝对比热，修正了VH应变处Δc/(γT)增大幅度的结论。
中文摘要 AI 辅助
单轴压力是量子材料的强大调控参数，但应变装置的受限几何结构难以实现比热等常规热力学测量。我们开发了用于交流（a.c.）弹热效应测量的定量分析框架，该框架可重构绝对熵及复杂相图范围内的比热。通过结合低频强耦合区测量与高频准绝热区高信噪比测量，实现了绝对精度。将该方法应用于关联超导体Sr$_2$RuO$_4$，我们获得了涵盖相图（包括超导态深处相变）的绝对熵映射。我们证明，从该数据可推导其他方法目前无法得到的绝对比热。该数据进一步证实：超导体Sr$_2$RuO$_4$内的熵淬灭在临界应变处最强，与超导能隙在范霍夫奇点（VHs）处最大化一致。此外，我们证明，尽管Δc/(γT)在VH应变处确实增大，但该增大幅度远小于此前更间接的量热实验推断值。
英文摘要
Uniaxial pressure is a powerful tuning parameter for quantum materials, but conventional thermodynamic probes such as specific heat are difficult to realize in the constrained geometries of strain apparatus. We develop a quantitative analysis framework for a.c. elastocaloric effect measurements that enable the reconstruction of the absolute entropy and hence specific heat across complex phase diagrams. The absolute accuracy is achieved by combining measurements in the strong coupling regime at low frequencies with high signal-to-noise measurements in the quasi-adiabatic regime at high frequencies. Applying the approach to the correlated superconductor Sr$_2$RuO$_4$, we obtain an absolute entropy map across the phase diagram including across phase transitions deep into the superconducting state. We demonstrate that from such data one can derive the absolute specific heat which is currently not possible through other approaches. This data reinforces the finding that the quenching of entropy within the superconductor Sr$_2$RuO$_4$ is strongest at the critical strain consistent with the superconducting gap being maximized at the Van Hove singularity (VHs). Furthermore, we demonstrate that, although $Δc /(γT) $ does increase at the VH strain, this increase is much weaker than previously inferred from more indirect caloric experiments.
