Superconductivity of Bi-III phase of elemental Bismuth: insights from Muon-Spin Rotation and Density Functional Theory

• Published in: arXiv.org
• Main Authors: Khasanov, Rustem, Luetkens, Hubertus, Morenzoni, Elvezio, Simutis, Gediminas, Schönecker, Stephan, Östlin, Andreas, Chioncel, Liviu, Amato, Alex
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 06.02.2019
• Subjects: Bismuth; Coherence length; Coupling; Density functional theory; Energy gap; Fermi surfaces; Ginzburg-Landau parameter; Muon spin rotation; Nesting; Penetration depth; Phase transitions; Physics - Superconductivity; Rotation; Superconductivity; Superconductors; Temperature dependence; Transition temperature
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1802.07139

Using muon-spin rotation the pressure-induced superconductivity in the Bi-III phase of elemental Bismuth (transition temperature \(T_{\rm c}\simeq7.05\) K) was investigated. The Ginzburg-Landau parameter \(\kappa=\lambda/\xi=30(6)\) (\(\lambda\) is the magnetic penetration depth, \(\xi\) is the coherence length) was estimated which is the highest among single element superconductors. The temperature dependence of the superconducting energy gap [\(\Delta(T)\)] reconstructed from \(\lambda^{-2}(T)\) deviates from the weak-coupled BCS prediction. The coupling strength \(2\Delta/k_{\rm B}T_{\rm c}\simeq 4.34\) was estimated thus implying that Bi-III stays within the strong coupling regime. The Density Functional Theory calculations suggest that superconductivity in Bi-III could be described within the Eliashberg approach with the characteristic phonon frequency \(\omega_{\rm ln}\simeq 5.5\) meV. An alternative pairing mechanism to the electron-phonon coupling involves the possibility of Cooper pairing induced by the Fermi surface nesting.