Anomalous linewidth of electron spin resonance in Langmuir-Blodgett films of the 3:2 complex of tetramethyltetrathiafulvalene and tetradecyltetracyanoquinodimethane

Abstract

Langmuir-Blodgett (LB) films of (tetramethyltetrathiafulvalene) 3-(tetradecyltetracyanoquinodimethane) 2 exhibit a high bulk conductivity and a metallic nature inside the domains in the system has already been suggested. The characteristic temperature dependence of the electron spin resonance (ESR) signal was observed for this system and the possible occurrence of Peierls fluctuations around 150 K has been reported. These fluctuations can be characterized by the maximum of the temperature-dependent ESR linewidth. We report here that the maximum of the linewidth is reversibly changed by the total pressure of the atmosphere in which the samples were sealed. A dependence on sealing gas species could not be detected, suggesting that chemical processes are not responsible for the anomalous behaviour of the linewidth. This phenomenon may be related to the flexible layered structure, which is characteristic of LB films.