Fractionalized topological insulators from frustrated spin models in three dimensions

TL;DR

This paper proposes a theoretical model for three-dimensional fractionalized topological insulators as U(1) spin liquids with gapped fermionic spinons and protected surface states, arising from frustrated spin interactions on a pyrochlore lattice.

Contribution

It introduces a new theoretical framework for 3D fractionalized topological insulators derived from frustrated spin models with emergent spin-orbit coupling.

Findings

Identification of a stable fractionalized topological insulator phase

Emergence of bulk bond spin-nematic order

Description of low energy properties of the state

Abstract

We present a theory of three dimensional fractionalized topological insulators in the form of U(1) spin liquids with gapped fermionic spinons in the bulk and topologically protected gapless spinon surface states. Starting from a spin-1/2 model on a pyrochlore lattice, with frustrated antiferromagnetic and ferromagnetic exchange interactions, we show that decomposition of the latter interactions, within slave-fermion representation of the spins, can naturally give rise to an emergent spin-orbit coupling for the spinons. This stabilizes a fractionalized topological insulators which also have bulk bond spin-nematic order. Finally, we describe the low energy properties of these states.