Odd-parity superconductivity from dipolar fluctuations in doped Bi₂Se₃

Doped Bi₂Se₃ is an unconventional superconductor with a nematic two-component order parameter, most likely of the p-wave symmetry. Yet the absence any nearby instabilities has made explaining the pairing mechanism difficult. Here we propose dipolar fluctuations as the pairing glue. We show that strong spin-orbit coupling mixes orbitals of opposite parities in doped Bi₂Se₃, inducing a finite dipolar density on the Fermi surface. The k_z-dependence of this mixing, which is closely related to the topological insulator state of the undoped compound, makes p-wave the preferred pairing channel under very natural assumptions.