Influence of the cooling rate on low-temperature Raman and infrared reflection spectra of partially deuterated k-(BEDT-TTF)_2Cu[N(CN)_2]Br

TL;DR

This study investigates how different cooling rates affect the low-temperature Raman and IR spectra of partially deuterated k-(BEDT-TTF)_2Cu[N(CN)_2]Br, revealing disorder-related spectral changes.

Contribution

It demonstrates the impact of cooling rate on spectral features in partially deuterated samples, highlighting disorder effects in these organic conductors.

Findings

Spectral features depend on cooling rate in deuterated samples

Disorder influences vibrational mode splitting and linewidths

Resonance enhancement varies with cooling conditions

Abstract

Raman and IR spectra of k-(BEDT-TTF)_2Cu[N(CN)_2]Br [BEDT-TTF denotes bis(ethylenedithiolo)tetrathiafulvalene] and its deuterated and partially deuterated analogues were measured at temperatures between 5 and 300 K and cooling rates from 1 to 20 K/min. It was found that, in partially deuterated samples, the interdimer electron-molecular vibration splitting of nu_3 mode in Raman spectra, the magnitude of the resonance enhancement in Raman spectra, and linewidths of some phonon peaks both in Raman and infrared spectra depend on the cooling rate. These observations were explained by disorder-related effects.