Metal-insulator transition in highly conducting oriented polymers

Physical Review B - Condensed Matter and Materials Physics

Volumn 56, Issue 6, 1997, Pages 3086-3093

  Dupuis, N ^a  

^a Bldg 142   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 1542361738     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.56.3086     Document Type: Article

References (21)

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17. N. Dupuis (unpublished).
18. See also the study of the instabilities of coupled Luttinger liquids by D. Boies, C. Bourbonnais, and A.-M. S. Tremblay, Phys. Rev. Lett. 74, 968 (1995); Correlated Fermions and Transport in Mesoscopic Systems, Proceedings of the XXXI(Formula presented) Rencontres de Moriond, series: Moriond Condensed Matter Physics, France, 1996, edited by T. Martin, G. Montambaux, and J. Tra⁁n Thanh Va⁁n (Éditions Frontières, Gif-sur-Yvette, 1996).
19. For a review on the NL(Formula presented)M approach to Anderson localization, see D. Belitz and T. R. Kirkpatrick, Rev. Mod. Phys. 66, 261 (1994).
20. A. G. McDiamird, Y. Min, J. M. Wiesinger, E. J. Oh, E. M. Scherr, and A. J. Epstein, Synth. Met. 55-57, 753 (1993).
21. M. Reghu, K. Vakiparta, Y. Cao, and D. Moses, Phys. Rev. B 49, 16 162 (1994). These authors report that for iodine-doped (CH)(Formula presented) the conductivity is found to increase a little for moderate pressure (up to 4 kbar) and decrease for greater pressure. We believe that there is no disagreement between this experimental result and the model studied in this paper or in Ref. 3. (i) Application of a moderate pressure should increase the strength of the interwire coupling and therefore the dimensionless coupling (Formula presented). Clearly a moderate pressure cannot change the number of interfibril contacts (this would require a significant change of the relative positions of the fibrils and therefore a rather strong pressure) so that the parameter (Formula presented) is not changed. As shown in Fig. 44, an increase of (Formula presented) at fixed (Formula presented) increases the conductivity. This effect is not expected to be very large (as shown in Fig. 44, the conductivity is more sensitive to a change of (Formula presented) than of (Formula presented) so that there is a rather nice agreement between theory and experiment as long as the pressure is not too strong. (ii) As reported by Reghu et al., the decrease of the conductivity above 4 kbar is not fully reversible. It is very likely that this irreversibility is due to a change in the structure of the polymer (modification of the relative positions of the fibrils) which in turn induces additional defects (hence the irreversibility) and decreases the conductivity.