Charge glass in an extended dimer Hubbard model

TL;DR

This paper investigates how frustration in an extended dimer Hubbard model causes glassy charge dynamics, providing insights into relaxor ferroelectric behavior observed in organic charge transfer salts.

Contribution

It introduces a classical effective model incorporating site occupations on neighboring dimers and demonstrates how frustration leads to charge glassiness without spin order.

Findings

Frustration induces charge glassiness in the model.

Charge glassiness occurs without spin ordering.

Results relate to relaxor ferroelectric behavior in experiments.

Abstract

The charge degrees of freedom in several different organic charge transfer salts display slow or glassy dynamics. In order to gain insight into this behaviour, we obtain the low energy theory for an extended dimer Hubbard model, taking into account the occupations of sites on neighbouring dimers. We take a classical limit of the resulting effective model of coupled spins and dimers and study it using classical Monte Carlo simulations. We find that frustration induced by intra- and inter-dimer interactions leads to glassiness in the charge degress of freedom in the absence of ordering of the spin degrees of freedom. Our results may have relevance to experimental observations of relaxor ferroelectric behaviour in the dynamics of organic charge transfer salts.