Electronic orders near the type-II van Hove singularity in BC${}_3$

Abstract

Using the functional renormalization group, we investigate the electron instability in the single-sheet BC${}_3$ when the electron filling is near a type-II van Hove singularity. For a finite Hubbard interaction, the ferromagnetic-like spin density wave order dominates in the immediate vicinity of the singularity. Elsewhere near the singularity the p-wave superconductivity prevails. We also find that a small nearest-neighbor Coulomb repulsion can enhance the superconductivity. Our results show that BC${}_3$ would be a promising candidate to realize topological $p+i{p}^{\prime }$ superconductivity, but the transition temperature is practically sizable only if the local interaction is moderately strong.

6 pages, 6 color figures. arXiv admin note: text overlap with arXiv:1503.00471