Bimodal energy relaxations in quasi-one-dimensional systems

TL;DR

This study investigates how low-temperature energy relaxation behaviors in quasi-one-dimensional systems vary with their ground state type, revealing distinct relaxation spectra for incommensurate and commensurate states linked to defect dynamics.

Contribution

It provides new insights into the different relaxation mechanisms in quasi-1D compounds based on their ground state commensurability, highlighting the role of defect dynamics.

Findings

Incommensurate states show a homogeneous shift in relaxation time distribution with heat input duration.

A scaling relation $w^{2} o ext{ln}( au_{m})$ is observed in incommensurate states.

Commensurate states exhibit bimodal relaxation spectra with distinct slow and fast components.

Abstract

We show that the low temperature ($T<0.5$ K) time dependent non-exponential energy relaxation of quasi-one-dimensional (quasi-1D) compounds strongly differ according to the nature of their modulated ground state. For incommensurate ground states, such as in (TMTSF)$_2$PF$_6$ the relaxation time distribution is homogeneously shifted to larger time when the duration of the heat input is increased, and exhibits in addition a scaling between the width and the position of the peak in the relaxation time distribution, $w^{2}\sim\ln{(\tau_{m})}$. For a commensurate ground state, as in (TMTTF)$_2$PF$_6$, the relaxation time spectra show a bimodal character with a weight transfer between well separated slow and fast entities. Our interpretation is based on the dynamics of defects in the modulated structure, which depend crucially on the degree of commensurability.