Time reversal symmetry broken fractional topological phases at zero magnetic field

TL;DR

This paper explores the emergence of fractional topological phases at zero magnetic field through coupled-wire models, revealing that spin interactions can induce time reversal symmetry breaking and stabilize novel fractional topological insulators.

Contribution

It extends the coupled-wire approach to identify new fractional topological phases with broken time reversal symmetry driven by spin interactions.

Findings

Fractional topological phases can be stabilized without external magnetic fields.

Spontaneous spin polarization and finite Hall conductivity indicate broken time reversal symmetry.

Fractional topological insulators may be inherently unstable to symmetry breaking.

Abstract

We extend the coupled-wire construction of quantum Hall phases, and search for fractional topological insulating states in models of weakly coupled wires at zero external magnetic field. Focussing on systems beyond double copies of fractional quantum Hall states at opposite fields, we find that spin-spin interactions can stabilize a large family of fractional topological phases with broken time reversal invariance. The latter is manifest by spontaneous spin polarization, by a finite Hall conductivity, or by both. This suggests the possibility that fractional topological insulators may be unstable to spontaneous symmetry breaking.