Nematicity and fractional magnetization plateaus induced by spin-lattice coupling in the classical kagome-lattice Heisenberg antiferromagnet

TL;DR

This study explores how spin-lattice coupling influences magnetic phases and plateaus in the classical kagome-lattice Heisenberg antiferromagnet, revealing nematic order and fractional magnetization plateaus through Monte Carlo simulations.

Contribution

It demonstrates the emergence of nematic order and fractional magnetization plateaus induced by spin-lattice coupling in the KHAF, using improved Monte Carlo methods.

Findings

Weak SLC preserves the degenerate ground state with a 1/3-magnetization plateau.

Strong SLC induces nematic order and a 1/9-magnetization plateau.

Near phase transitions, ergodicity breaks and slow dynamics occur.

Abstract

We investigate the effect of spin-lattice coupling (SLC) on the magnetic properties of the classical kagome-lattice Heisenberg antiferromagnet (KHAF) using improved Monte Carlo updates. The lattice modes are represented by Einstein site phonons, which introduce effective further-neighbor spin interactions in addition to the nearest-neighbor biquadratic interactions. In the weak SLC, the macroscopically degenerate coplanar ground state remains at zero field, while a $\sqrt{3} \times \sqrt{3}$ ordered phase accompanied by a 1/3-magnetization plateau appears in external magnetic fields. In the strong SLC, we find a nematic order at zero field and a 1/9-magnetization plateau associated with a $3 \times 3$ collinear order. Near the phase transition between the 1/9- and 1/3-plateau states, the ergodicity in the single spin flip is practically broken, and slow dynamics appear. We propose that relevant KHAFs with strong SLC would be realized in spinel-based materials.