Freezing and large time scales induced by geometrical frustration

TL;DR

This paper studies a frustrated spin system, revealing low-temperature freezing of chiralities and slow spin dynamics akin to spin glasses, using classical Monte Carlo simulations.

Contribution

It introduces an effective Hamiltonian for a trimerized kagome antiferromagnet and uncovers novel low-temperature behaviors driven by geometrical frustration.

Findings

Chiralities freeze dynamically at low temperatures.

Lattice decouples into dimers and triangles.

External magnetic field induces slow spin dynamics.

Abstract

We investigate the properties of an effective Hamiltonian with competing interactions involving spin and chirality variables, relevant for the description of the {\it trimerized} version of the spin-1/2 {\it kagome} antiferromagnet. Using classical Monte Carlo simulations, we show that remarkable behaviors develop at very low temperatures. Through an {\it order by disorder} mechanism, the low-energy states are characterized by a dynamical freezing of the chiralities, which decouples the lattice into ``dimers'' and ``triangles'' of antiferromagnetically coupled spins. Under the presence of an external magnetic field, the particular topology of the chiralities induces a very slow spin dynamics, reminiscent of what happens in ordinary spin glasses.