# Chiral spin liquids with crystalline $\mathbb{Z}_2$ gauge order in a three-dimensional Kitaev model

## TL;DR

This paper reports the discovery of three-dimensional chiral spin liquids in a Kitaev model, characterized by crystalline $$ gauge flux order, topological Majorana fermions, and a rich phase diagram with multiple CSL phases.

## Contribution

It demonstrates the existence of 3D chiral spin liquids with crystalline gauge order in a Kitaev model, using quantum Monte Carlo and variational methods, revealing multiple distinct phases.

## Key findings

- CSLs exhibit crystalline $$ gauge flux order and break lattice symmetries.
- Multiple CSL phases with topological Majorana fermions, including Weyl nodes and Fermi arcs.
- A first-order transition separates CSLs from the paramagnetic phase.

## Abstract

Chiral spin liquids (CSLs) are time-reversal symmetry breaking ground states of frustrated quantum magnets that show no long-range magnetic ordering, but instead exhibit topological order and fractional excitations. Their realization in simple and tractable microscopic models has, however, remained an open challenge for almost two decades until it was realized that Kitaev models on lattices with odd-length loops are natural hosts for such states, even in the absence of a time-reversal symmetry breaking magnetic field. Here we report on the formation of CSLs in a three-dimensional Kitaev model, which differ from their widely studied two-dimensional counterparts, namely, they exhibit a crystalline ordering of the $\mathbb{Z}_2$ gauge fluxes and thereby break some of the underlying lattice symmetries. We study the formation of these unconventional CSLs via extensive quantum Monte Carlo simulations and demonstrate that they are separated from the featureless paramagnet at high temperatures by a single first-order transition at which both time-reversal and lattice symmetries are simultaneously broken. Using variational approaches for the ground state, we explore the effect of varying the Kitaev couplings and find at least five distinct CSL phases, all of which possess crystalline ordering of the $\mathbb{Z}_2$ gauge fluxes. For some of these phases, the complementary itinerant Majorana fermions exhibit gapless band structures with topological features such as Weyl nodes or nodal lines in the bulk and Fermi arc or drumhead surface states.