Dependence of Peierls transition on carrier concentration in quasi-one-dimensional organic crystals of TTT2I3
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ANDRONIC, Silvia, KASIYAN, Anatolie. Dependence of Peierls transition on carrier concentration in quasi-one-dimensional organic crystals of TTT2I3. In: Materials Science and Condensed Matter Physics, Ed. 9, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, Ediția 9, p. 71.
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Materials Science and Condensed Matter Physics
Ediția 9, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics"
9, Chișinău, Moldova, 25-28 septembrie 2018

Dependence of Peierls transition on carrier concentration in quasi-one-dimensional organic crystals of TTT2I3

CZU: 538.9+544

Pag. 71-71

Andronic Silvia, Kasiyan Anatolie
 
Technical University of Moldova
 
Disponibil în IBN: 15 ianuarie 2019


Rezumat

Quasi-one-dimensional organic crystals of TTT2I3 have demonstrated prospect thermoelectric properties. In the same time, these crystals with the lowering temperature show a metal-dielectric transition. Earlier we have demonstrated for a crystal with the composition TTT2I3.1 that the transition is of Peierls type. The transition begins at T ~ 35 K in TTT chains. Due to interchain interaction the transition is finished at T ~ 9.8 K. As it is observed experimentally, the electrical conductivity has a maximum at 35 K and achieves zero at T ~ 10 K.  The TTT2I3 crystals are formed of segregate chains of TTT and of iodine. TTT2I3 is a charge transfer compound. The compound is of mixed valence. Two molecules of TTT give one electron to iodine chain formed of I3 ions that play the role of acceptors. But the crystals admit non stoichiometric composition with surplus or deficiency of iodine. Therefore, the metal-dielectric transition takes place at different carrier concentrations.  The aim of this paper is to investigate how this transition depends on carrier concentration. We apply a more complete physical model that consider simultaneously two the most important electronphonon interactions. The first is similar to that of deformation potential and the second one is of polaron type. The dynamical interaction of carriers with the defects is also taken into account. The analytic expression for the phonon Green function is obtained in the random phase approximation. Fig. 1. Renormalized phonon spectrum Ω(qx) for γ1 = 1.7, kF = (0.517п/2)-0.018 and different temperatures. The dashed line is for the spectrum of free phonons. In this case  qy = 0, qz = 0.