Archimedes and the spins

Quantum spin liquids have attracted a lot of attention in condensed matter physics, both from a theoretical and an experimental perspective. A revolution in the field occurred when Kitaev introduced an exactly solvable model for an Abelian quantum spin liquid on a honeycomb lattice. The solvability of the model lends itself to a more concise connection to candidate materials.

In this work, we consider a variation of the Kitaev model defined on a lattice realized by the proliferation of Stone-Wales defects: A pair of honeycomb bonded vertices change their connectivity as they rotate by 90 degrees with respect to the midpoint of their bond. The resulting lattice is a non-Archimedean one, where neither all sites nor all bonds are equivalent. This minimal change to the lattice has striking effects. In fact, our system realizes an exactly solvable instance of a non-Abelian gapped chiral spin liquid.

We believe that the exact solvability of our model and its tight connection to the simpler model defined on a honeycomb lattice will bring chiral spin liquids closer to experimental observation. For example, ab-initio calculations show that moderate amount of strain in alpha-RuCl3, one of the most promising Kitaev materials candidate, is sufficient to stabilize the non-Archimedean lattice proposed in our model.