Pressure-tuned magnetic interactions in honeycomb Kitaev materials

TL;DR

This study investigates how pressure influences magnetic interactions in honeycomb Kitaev materials, revealing that pressure can enhance Kitaev interactions relative to Heisenberg interactions, potentially stabilizing a spin liquid state.

Contribution

The paper demonstrates how pressure differentially affects Kitaev and Heisenberg interactions in honeycomb compounds using advanced quantum-chemistry methods, offering a pathway to stabilize spin liquids.

Findings

Kitaev interactions increase more rapidly than Heisenberg interactions under pressure.

Pressure can be used to tune magnetic interactions towards a spin liquid state.

Different compounds respond uniquely to pressure, affecting their magnetic properties.

Abstract

A range of honeycomb-lattice compounds has been proposed and investigated in the search for a topological Kitaev spin liquid. However, sizable Heisenberg interactions and additional symmetry-allowed exchange anisotropies in the magnetic Hamiltonian of these potential Kitaev materials push them away from the pure Kitaev spin-liquid state. Particularly the Kitaev-to-Heisenberg coupling ratio is essential in this respect. With the help of advanced quantum-chemistry methods, we explore how the magnetic coupling ratios depend on pressure in several honeycomb compounds (Na$_2$IrO$_3$, $\beta$-Li$_2$IrO$_3$, and $\alpha$-RuCl$_3$). We find that the Heisenberg and Kitaev terms are affected differently by uniform pressure or strain: the Kitaev component increases more rapidly than the Heisenberg counterpart. This provides a scenario where applying pressure or strain can stabilize a spin liquid in such materials.