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Pressure driven neutral-ionic transition in ClMePD-DMeDCNQI

Luca Farina·Aldo Brillante·Matteo Masino·Alberto Girlando
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Abstract

Application of about 0.8 GPa pressure is sufficient to induce the neutral-ionic transition in the mixed stack charge-transfer crystal 2-chloro-5-methyl-$p$-phenylenediamine--2,5-dimethyl-dicyanoquinonediimine ({\CD}). The ionicity increases continuously from $\sim$ 0.35 at ambient conditions to $\sim$ 0.65 when the pressure is raised up to 2 GPa. Moreover, stack dimerization begins well before the crossing of the neutral-ionic interface. The evolution of the transition is similar to what observed in the temperature induced phase change in the same compound. (cond-mat/0101179) A distinguishing feature is represented by the simultaneous presence of domains of molecules with slightly different ionicities across the transition pressure. A comparison of the present example of pressure driven neutral-ionic transition with the well studied cases of tetrathiafulvalene--chloranil and of tetrathiafulvalene--2,5-dichloro-p-benzoquinone puts in evidence the remarkably different evolution of the three transitions.

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Luca Farina, Aldo Brillante, Matteo Masino, Alberto Girlando. 2001-05-07. Pressure driven neutral-ionic transition in ClMePD-DMeDCNQI. https://doi.org/10.1103/physrevb.64.144102

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