QUANTUM MECHANISMS OF DENSITY WAVE TRANSPORT
Wijesinghe, Asanga 1978-
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The non-linear properties observed in charge density wave compounds have been studied for many years. The quasi one-dimensional conductor NbSe3 is particularly important because a small electric field can depin the charge density wave above a threshold field, above which the charge density wave shows Zener-type non-linear behavior. Transport properties of the one-dimensional linear chain compound NbSe3 is measured using dc measurement, ac measurement, pulse techniques, direct mixing, and harmonic mixing as a function of dc bias voltage, applied frequencies, and in some cases the amplitude of an additional ac signal source. A phenomenological model, consisting of a shunt resistance in parallel with tunnel junction capacitor, based on the Hamiltonian tunneling matrix element is presented as a possible mechanism for correctly describing charge density wave dynamics. Our results appear to be consistent with time-correlated quantum nucleation of solitons and antisolitons. Furthermore, mixing experiment results are also compared with photon-assisted tunneling theory. Numerical calculations obtained from the model accurately reproduce the observed feature of charge density wave dynamics. The results reported here thus provide compelling evidence in favor of quantum tunneling as the mechanism for charge density wave depinning and transport.