Superconductivity in three-dimensional spin-orbit coupled semimetals

Article

关键词: HALF-HEUSLER COMPOUNDS;    SEMICONDUCTORS;   

DOI  :  10.1103/PhysRevB.96.214514

来源: SCIE

【 摘 要 】

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.

【 授权许可】

Free