Chiral d-wave superconductivity in doped graphene

TL;DR

This paper reviews theoretical evidence for chiral d-wave superconductivity in doped graphene, highlighting its unique properties, stability, and potential enhancement methods, and compares it with other candidate materials.

Contribution

It compiles and discusses diverse theoretical approaches supporting the existence of chiral d-wave superconductivity in doped graphene and explores its properties and stability.

Findings

Theoretical evidence supports chiral d-wave pairing in doped graphene.

Chiral d-wave state exhibits topological and edge current properties.

Proximity effects can enhance chiral d-wave superconductivity.

Abstract

A highly unconventional superconducting state with a spin-singlet $d_{x^2-y^2}\pm id_{xy}$-wave, or chiral d-wave, symmetry has recently been proposed to emerge from electron-electron interactions in doped graphene. Especially graphene doped to the van Hove singularity at 1/4 doping, where the density of states diverges, has been argued to likely be a chiral d-wave superconductor. In this review we summarize the currently mounting theoretical evidence for the existence of a chiral d-wave superconducting state in graphene, obtained with methods ranging from mean-field studies of effective Hamiltonians to angle-resolved renormalization group calculations. We further discuss multiple distinctive properties of the chiral d-wave superconducting state in graphene, as well as its stability in the presence of disorder. We also review means of enhancing the chiral d-wave state using proximity-induced superconductivity. The appearance of chiral d-wave superconductivity is intimately linked to the hexagonal crystal lattice and we also offer a brief overview of other materials which have also been proposed to be chiral d-wave superconductors.