Evidence of unconventional superconductivity on the surface of the nodal semimetal CaAg1−xPdxP

Surface states of topological materials provide extreme electronic states for unconventional superconducting states. CaAg 1− x Pd x 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 1− x Pd x P has surface st...

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Published inNature communications Vol. 14; no. 1; p. 6817
Main Authors Yano, Rikizo, Nagasaka, Shota, Matsubara, Naoki, Saigusa, Kazushige, Tanda, Tsuyoshi, Ito, Seiichiro, Yamakage, Ai, Okamoto, Yoshihiko, Takenaka, Koshi, Kashiwaya, Satoshi
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 26.10.2023
Nature Publishing Group
Subjects
639/301/119/1003
639/301/119/2792/4128
Electron states
Fermi surfaces
Humanities and Social Sciences
Ionic liquids
Magnetoresistance
Magnetoresistivity
Mobility
multidisciplinary
Science
Science (multidisciplinary)
Spectroscopy
Spectrum analysis
Unconventional superconductivity
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Summary:Surface states of topological materials provide extreme electronic states for unconventional superconducting states. CaAg 1− x Pd x 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 1− x Pd x 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 c ) 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. CaAg 1− x Pd x P is a nodal-line Dirac semimetal. Here, using ionic-liquid gated transport and soft point-contact spectroscopy, the authors show that this material realizes surface-confined unconventional superconductivity.
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ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-023-42535-5