Soliton Analysis of the ElectroOptical Response of Blue Bronze.pdf

SOLITON ANALYSIS OF THE ELECTRO-OPTICAL RESPONSE OF BLUE BRONZE J.W. Brill* Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055, USA ABSTRACT In recent measurements on the charge-density-wave (CDW) conductor blue bronze (K MoO ), the electro-transmittance and electro-reflectance spectra were searched for 0.3 3 intragap states that could be associated with solitons created by injection of electrons into the CDW at the current contacts [Eur. Phys. J. B 16, 295 (2000); ibid 35, 233 (2003)]. In this work, we adapt the model of soliton absorption in dimerized polyacetylene to the blue bronze results, to obtain the (order of magnitude) estimate that current induced solitons occur on less than ~ 10% of the conducting chains. We discuss the implications of these results on models of soliton lifetimes and motion of CDW phase dislocations. PACS: 71.45.Lr, 78.20.Jq Keywords: A. Charge-density-wave, D. optical properties, D. electronic transport * jwbrill@uky.edu ; Tel: 1-859-257-4670; FAX: 1-859-323-2846 The phenomenon of collective transport by sliding charge-density-waves (CDWs) in quasi-one dimensional conductors has been known for almost three decades [1,2], but our understanding of the details of “current conversion”, i.e. how electrons enter and leave the CDW at current contacts, has remained incomplete. Macroscopically, conversion is believed to occur through CDW phase-slip, occurring through the climb of CDW phase dislocations across the sample cross-section [3]. In a series of elegant transport measurements on the semimetallic CDW conductor, NbSe [1], the Cornell group has 3 shown how phase-slip is driven by longitudinal strains in the CDW [4]. The strain profiles they dedu