Chiral and topological superconductivity in isospin polarized multilayer graphene

TL;DR

This paper proposes a microscopic mechanism for chiral topological superconductivity in isospin polarized multilayer graphene, revealing a transition from trivial to topological phases with Majorana fermions near a Lifshitz transition.

Contribution

It introduces a novel Coulomb-repulsion-driven chiral superconductivity mechanism in multilayer graphene with topological phase transition insights.

Findings

Superconductivity occurs at low density with chiral p-wave symmetry.

Highest T_c near a Lifshitz transition from annular to simply-connected Fermi sea.

Topological phase transition hosts Majorana fermions.

Abstract

A microscopic mechanism for chiral superconductivity from Coulomb repulsion is proposed for spin- and valley-polarized state of rhombohedral multilayer graphene. The superconducting state occurs at low density, has chiral $p$-wave pairing symmetry, and exhibits highest $T_c$ close to a Lifshitz transition from annular to simply-connected Fermi sea. This Lifshitz transition also marks a topological phase transition from a trivial to a topological superconducting phase hosting Majorana fermions. The chirality of the superconducting order parameter is selected by the chirality of the valley-polarized Bloch electrons. Our results are in reasonable agreement with observations in a recent experiment on tetralayer graphene [arXiv:2408.15233]