Abstract
Despite intense experimental efforts, the nature of the unconventional superconducting order parameter of remains elusive. This puzzle stems from reports of either a single or a double superconducting transition at ambient pressure as well as a complex pressure-temperature phase diagram. To address this issue, we measured the heat capacity and electrical resistivity of under compressive uniaxial stress applied along different crystallographic directions. We find that the critical temperature of the single observed bulk superconducting transition decreases with along [100] and [110] but increases with along [001]. Aside from its effect on , -axis stress leads to a significant piezoresistivity. Importantly, an in-plane shear stress does not induce any observable splitting of the superconducting transition over a stress range of . This result suggests that the superconducting order parameter of may be single component at ambient pressure.
- Received 25 May 2022
- Accepted 26 July 2022
DOI:https://doi.org/10.1103/PhysRevB.106.L121101
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