dc-conduction mechanism and Peierls gap in organic and inorganic charge-density-wave conductors

Non-Maxwell-Boltzmann dependence of channel carrier concentration in a quasi one dimensional charge density wave channel in the ballistic transport regime

With the aid of a coherent transport model utilizing the non-equilibrium Green function approach, a three terminal device with metallic gate, source and drain and a quasi one dimensional charge density wave (CDW) channel is simulated focussing on the transistor behaviour brought about by a sweep of the channel potential or equivalently the chemical potential in the channel. The channel is strongly insulating only at half-filling and moving to lower and higher carrier concentrations both incur a mean field phase transition to a conducting state. With the aid of conductance calculations for a pinned CDW condensate, we present calculations for the sub-threshold slope in terms of the hopping parameter or equivalently the width of the tight-binding chain. The effects of source to drain bias and length are examined. The conductance profiles are analyed in relation to transmission profiles. The observed CDW profiles are explained in terms of filling and Fermi surface nesting. Boundary conditions, gap equations and response functions are shown to reveal the commensurability conditions and size of the transport gap. The channel carrier concentration is modulated in an athermal (non-Maxwellian-Boltzmann) fashion, thereby making it an interesting prospect for steep transistors.

Band-selective Holstein polaron in Luttinger liquid material A0.3MoO3 (A = K, Rb)

(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A_0.3MoO₃ (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A_0.3MoO₃ is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which are recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays an important role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study interesting excitations in Luttinger liquid materials.

Diffusive diffraction of the local ESR pulse-gradient spin-echo signal in a restricted one-dimensional conductor

The diffusive motion of the conducting electrons in the one-dimensional organic conductor FA2PF6 (FA, Fluoranthene) is studied with the ESR pulse-gradient spin-echo (PGSE) signal combined with spatial density ESR imaging. A local measurement of the short restricted regions reveals diffraction patterns in the local PGSE data. A model calculation adapted to the local measurements provides a highly accurate quantitative description of the results. The appearance of these patterns provides information about the diffusive motion of the charge at the crystal boundaries.