Pressure driven neutral-ionic transition in ClMePD-DMeDCNQI
arXiv:cond-mat/0105134 · doi:10.1103/PhysRevB.64.144102
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--phenylenediamine--2,5-dimethyl-dicyanoquinonediimine ({\CD}). The ionicity increases continuously from 0.35 at ambient conditions to 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.
6 pages in *.PS format, 5 figures