Unconventional pressure dependence of the superfluid density in the nodeless topological superconductor $\alpha$-PdBi$_2$

Debarchan Das; Ritu Gupta; Christopher Baines; Hubertus Luetkens; Dariusz Kaczorowski; Zurab Guguchia; Rustem Khasanov

doi:10.1103/physrevlett.127.217002

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arXiv · 2202.10859

Unconventional pressure dependence of the superfluid density in the nodeless topological superconductor $\alpha$-PdBi$_2$

Debarchan Das·Ritu Gupta·Christopher Baines·Hubertus Luetkens·Dariusz Kaczorowski·Zurab Guguchia·Rustem Khasanov

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Abstract

We investigated the superconducting properties of the topological superconductor $\alpha$--PdBi$_2$ at ambient and external pressures up to 1.77~GPa using muon spin rotation ($\mu$SR) experiments. The ambient pressure measurements evince a fully gapped $s$-wave superconducting state in the bulk of the specimen. AC magnetic susceptibility and $\mu$SR measurements manifest a continuous suppression of $T_{\rm c}$ with increasing pressure. In parallel, we observed a significant decrease of superfluid density by $\sim$20\% upon application of external pressure. Remarkably, the superfluid density follows linear relation with $T_{\rm c}$ which was found before in some unconventional topological superconductors and hole doped cuprates. This finding signals a possible crossover from BEC to BCS in $\alpha$--PdBi$_2$.

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Debarchan Das, Ritu Gupta, Christopher Baines, Hubertus Luetkens, Dariusz Kaczorowski, Zurab Guguchia, Rustem Khasanov. 2022-02-22. Unconventional pressure dependence of the superfluid density in the nodeless topological superconductor $\alpha$-PdBi$_2$. https://doi.org/10.1103/physrevlett.127.217002

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