Abstract

Recent experiments support that magic-angle graphene can be modeled by a periodic array of correlated quantum impurities immersed in a Dirac sea. This work analytically studies a spin-valley Anderson impurity with general valley-anisotropic (anti-)Hund’s interaction originating from electron-phonon couplings, derives its phase diagram, and identifies a unified origin for pairing potential and pseudogap. The analysis shows a BKT transition to an anisotropic doublet phase and a second-order transition to a local singlet phase, with numerical renormalization group calculations used for verification and for correlation/self-energy ansätze relevant to magic-angle graphene.

Abstract

Recent experiments support that magic-angle graphene can be modeled by a periodic array of correlated quantum impurities immersed in a Dirac sea. This work analytically studies a spin-valley Anderson impurity with general valley-anisotropic (anti-)Hund’s interaction originating from electron-phonon couplings, derives its phase diagram, and identifies a unified origin for pairing potential and pseudogap. The analysis shows a BKT transition to an anisotropic doublet phase and a second-order transition to a local singlet phase, with numerical renormalization group calculations used for verification and for correlation/self-energy ansätze relevant to magic-angle graphene.

Abstract

Recent experiments support that magic-angle graphene can be modeled by a periodic array of correlated quantum impurities immersed in a Dirac sea. This work analytically studies a spin-valley Anderson impurity with general valley-anisotropic (anti-)Hund’s interaction originating from electron-phonon couplings, derives its phase diagram, and identifies a unified origin for pairing potential and pseudogap. The analysis shows a BKT transition to an anisotropic doublet phase and a second-order transition to a local singlet phase, with numerical renormalization group calculations used for verification and for correlation/self-energy ansätze relevant to magic-angle graphene.

Abstract

Recent experiments support that magic-angle graphene can be modeled by a periodic array of correlated quantum impurities immersed in a Dirac sea. This work analytically studies a spin-valley Anderson impurity with general valley-anisotropic (anti-)Hund’s interaction originating from electron-phonon couplings, derives its phase diagram, and identifies a unified origin for pairing potential and pseudogap. The analysis shows a BKT transition to an anisotropic doublet phase and a second-order transition to a local singlet phase, with numerical renormalization group calculations used for verification and for correlation/self-energy ansätze relevant to magic-angle graphene.