Microwave emulations and tight-binding calculations of transport in polyacetylene

Thomas A Stegmann (1) , John P Franco-Villafañe (1, 2) , Yenni P Ortiz (1) , Ulrich Kuhl (3) , Fabrice Mortessagne (3) , Thomas H Seligman (1, 4)

1 Instituto de Ciencias Físicas
2 Instituto de Física, Benemérita Universidad Autónoma de Puebla
3 LPMC - Laboratoire de physique de la matière condensée
4 Centro Internacional de Ciencias

A novel approach to investigate the electron transport of cis-and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene.

Mots clés: coherent transport; polyacetylene; microwave emulation experiments; nonequilibrium Green's function method PACS

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]; Physique [physics]

Thomas A Stegmann, John P Franco-Villafañe, Yenni P Ortiz, Ulrich Kuhl, Fabrice Mortessagne, et al.. Microwave emulations and tight-binding calculations of transport in polyacetylene. Physics Letters A, 2017, 381 (1), pp.24-29. ⟨10.1016/j.physleta.2016.09.037⟩. ⟨hal-01375973⟩