Current-Induced Low-Resistance State and Its Crystal Structure of a TTF-Based Dimeric Donor Salt

摘要

A mixed-valence state, which comes from the resonance between two ions with different oxidation states, is one of important concepts for understanding the electronic structure of assembled materials. In the class Ⅰ state, the oxidation states of each site are fixed discretely (e.g., D°, D~(+1), D°, D~(+1), ...), whereas they are equalized by charge delocalization (e.g., D~(+1/2), D~(+1/2), D~(+1/2), ...) in the class Ⅲ state. This concept is applied to molecular solids successfully. Recently, we found that the conductivity of an ion-radical salt of a donor molecule in the class Ⅰ state increased drastically by application of a large current, and we explored the mechanism of this nonlinear response in the conductivity by analyzing the X-ray crystal structure of the salt during the current application.