Superconductivity in three-dimensional spin-orbit coupled semimetals
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PhysRevB.96.214514.pdf
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Author(s)
Savary, Lucile
Ruhman, Yehonatan
Venderbos, Joern Willem Friedrich
Fu, Liang
Lee, Patrick A
Date Issued
December 2017
Journal
Physical Review B
Publisher
American Physical Society
Citation
Savary, Lucile, et al. “Superconductivity in Three-Dimensional Spin-Orbit Coupled Semimetals.” Physical Review B, vol. 96, no. 21, Dec. 2017. © 2018 American Physical Society
Version
Final published version
Abstract
Motivated by the experimental detection of superconductivity in the low-carrier density half-Heusler compound YPtBi, we study the pairing instabilities of three-dimensional strongly spin-orbit coupled semimetals with a quadratic band touching point. In these semimetals the electronic structure at the Fermi energy is described by spin j=3/2 quasiparticles, which are fundamentally different from those in ordinary metals with spin j=1/2. For both local and nonlocal pairing channels in j=3/2 materials we develop a general approach to analyzing pairing instabilities, thereby providing the computational tools needed to investigate the physics of these systems beyond phenomenological considerations. Furthermore, applying our method to a generic density-density interaction, we establish that: (i) The pairing strengths in the different symmetry channels uniquely encode the j=3/2 nature of the Fermi surface band structure—a manifestation of the fundamental difference with ordinary metals. (ii) The leading odd-parity pairing instabilities are different for electron doping and hole doping. Finally, we argue that polar phonons, i.e., Coulomb interactions mediated by the long-ranged electric polarization of the optical phonon modes, provide a coupling strength large enough to account for a Kelvin-range transition temperature in the s-wave channel, and are likely to play an important role in the overall attraction in non-s-wave channels. Moreover, the explicit calculation of the coupling strengths allows us to conclude that the two largest non-s-wave contributions occur in nonlocal channels, in contrast with what has been commonly assumed.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.96.214514
