Amorphous and polycrystalline routes towards a chiral spin liquid

TL;DR

This paper demonstrates that chiral spin liquids can naturally form in amorphous or polycrystalline Kitaev materials due to spontaneous time-reversal symmetry breaking caused by odd-edged plaquettes, expanding potential realizations beyond crystalline systems.

Contribution

It introduces a mechanism for chiral spin liquid emergence in non-crystalline materials based on plaquette edge parity, supported by theoretical and numerical analysis.

Findings

Chiral spin liquids can form in amorphous and polycrystalline Kitaev materials.

The energy gap scales with the density of odd-edged plaquettes, reaching saturation.

Chiral spin liquids are stable against Heisenberg interactions similar to crystalline models.

Abstract

We show that a chiral spin liquid spontaneously emerges in partially amorphous, polycrystalline, or ion-irradiated Kitaev materials. In these systems, time-reversal symmetry is broken spontaneously due to a non-zero density of plaquettes with an odd number of edges, $n_{odd}$. This mechanism opens a sizeable gap, at small $n_{odd}$ compatible with that of typical amorphous materials and polycrystals, and which can alternatively be induced by ion-irradiation. We find that the gap is proportional to $n_{odd}$, saturating at $n_{odd}\sim 40\%$. Using exact diagonalization, we find that the chiral spin liquid is approximately as stable to Heisenberg interactions as Kitaev's honeycomb spin liquid model. Our results open up a significant number of non-crystalline systems where chiral spin liquids can emerge without external magnetic fields.