Interaction driven surface Chern insulator in nodal line semimetals

TL;DR

This paper demonstrates that electronic interactions in nodal line semimetals can induce a surface Chern insulator phase through ferromagnetic instability of the drumhead surface states, enabling dissipationless transport.

Contribution

It reveals a novel interaction-driven mechanism for creating surface Chern insulators in nodal line semimetals, highlighting their potential for topological electronic applications.

Findings

Interaction causes ferromagnetic instability in surface states

Surface states carry half-monopole charge leading to Chern number -1

Phenomenology is robust against chiral-symmetry breaking

Abstract

Nodal line semimetals are characterized by nontrivial bulk-band crossings, giving rise to almost flat drumhead-like surface states (DSS), which provide an attractive playground where interaction can induce symmetry-broken states and potential emergent phases. Here, we show that electronic interaction causes Stoner ferromagnetic instability in the DSS while the bulk remains non-magnetic, which together with spin-orbit coupling drive the surface states into a 2D Chern insulator. We show that each DSS carries a half-monopole charge, which for systems containing two pieces of DSS yield a net Chern number $\mathcal{C}=-1$. We show that this phenomenology is robust against chiral-symmetry breaking, that gives a finite dispersion to the DSS. Our work shows that nodal line semimetals are a promising platform to implement surface Chern insulators and dissipation-less electron transport by exploiting enhanced interaction effects of the DSS.