Heterogeneous freezing in a geometrically frustrated spin model without disorder: spontaneous generation of two time-scales

TL;DR

This paper investigates how geometrically frustrated classical spins exhibit spontaneous dynamical freezing and heterogeneities, leading to broken ergodicity and anomalous thermodynamic behavior without disorder.

Contribution

It demonstrates that geometrical frustration alone can induce dynamical heterogeneities and phase space fragmentation, resulting in self-induced disorder and thermodynamic anomalies.

Findings

Identification of a dynamical freezing temperature

Observation of metastable states with frozen moments

Fragmentation of phase space into disconnected sectors

Abstract

By considering the constrained motion of classical spins in a geometrically frustrated magnet, we find a dynamical freezing temperature below which the system gets trapped in metastable states with a "frozen" moment and dynamical heterogeneities. The residual collective degrees of freedom are strongly correlated, and by spontaneously forming aggregates, they are unable to reorganize the system. The phase space is then fragmented in a macroscopic number of disconnected sectors (broken ergodicity), resulting in self-induced disorder and "thermodynamic" anomalies, measured by the loss of a finite configurational entropy. We discuss these results in the view of experimental results on the kagome compounds, SrCr(9p)Ga(12-9p)O19, (H30)Fe3(SO4)2(OH)6, Cu3V2O7(OH)2.2H2O and Cu3BaV2O8(OH)2.