Evidence of unconventional superconductivity on the surface of the nodal semimetal CaAg<sub>1-x</sub>Pd<sub>x</sub>P.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37884509.
- Also identified by DOI 10.1038/s41467-023-42535-5 and PMC identifier 10603147.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Surface states of topological materials provide extreme electronic states for unconventional superconducting states. CaAg<sub>1-x</sub>Pd<sub>x</sub>P is an ideal candidate for a nodal-line Dirac semimetal with drumhead surface states and no additional bulk bands. Here, we report that CaAg<sub>1-x</sub>Pd<sub>x</sub>P has surface states that exhibit unconventional superconductivity (SC) around 1.5 K. Extremely sharp magnetoresistance, tuned by surface-sensitive gating, determines the surface origin of the ultrahigh-mobility "electrons." The Pd-doping elevates the Fermi level towards the surface states, and as a result, the critical temperature (T<sub>c</sub>) is increased up to 1.7 K from 1.2 K for undoped CaAgP. Furthermore, a soft point-contact study at the surface of Pd-doped CaAgP proved the emergence of unconventional SC on the surface. We observed the bell-shaped conductance spectra, a hallmark of the unconventional SC. Ultrahigh mobility carriers derived from the surface flat bands generate a new class of unconventional SC.