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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology

» presentations   » 1999.10




Correlated electron transport in 1d

 M. Sassetti , A. Fechner, G. Cuniberti, and B. Kramer

225th International Wilhelm Heinrich und Else Heraeus Seminar on ``Electron Transport in Reduced Dimensions - Concepts and Reality''

1999.10; Bad Honnef, Bonn, Germany

The dynamical interplay between currents and electromagnetic fields belongs to one of the fundamental and open problems. A key issue is to describe the ac-phenomena of quantum systems self-consistently, in the presence of correlations and non-linearity [1]. We address this topic for frequency dependent transport of interacting electrons in 1d. In the linear regime we determine the longitudinal and transverse ac-response. The space dependence of the local electromagnetic fields is evaluated self-consistently. As a particular example, we determine the complex absorptive conductance for a longitudinal ac field. It is analyzed in terms of resistive, capacitive and inductive contributions [2]. In the non-linear case we investigate ac-properties created by the presence of a tunnel barrier. ``Single charge tunneling'' is considered microscopically by calculating the time-dependent non-linear current response to a monochromatic external voltage. The DC current-voltage characteristics is calculated taking into account electron-electron interaction of finite-range [3]. For intermediate interaction strengths, the non-linear differential conductance shows cusp-like minima at integer ratios of the bias voltages with the driving frequency $\Omega$. This frequency-locking effect, is a signature of the systems coherent, strongly correlated electron states and it is characteristic of the finite, non-zero range of the interaction but does not depend on the exact shape of the driving electric field. However, the frequency-scaling of the photo-induced current shows a cross-over between -1 and -2, and depends on the spatial shape of the driving field. Due to intrinsic non-linearity, the system shows also harmonic generation. We explicitly evaluate the current and discuss the non-Fermi liquid dependence on the interaction strength [4]. Quantitative results for the electromagnetic radiation are provided especially in the near field region. Specifically, we demonstrate that the electromagnetic power is emitted perpendicular to the quantum wire close to the tunnel barrier, while it is radiated parallel to the wire away from the barrier.

[1] O. Keller, Phys. Rep. 268, 85 (1996).
[2] G. Cuniberti, M. Sassetti, B. Kramer, Phys. Rev. B57, 1515 (1998).
[3] G. Cuniberti, A. Fechner, M. Sassetti, B. Kramer, preprint
[4] A. Fechner, M. Sassetti, B. Kramer, Europhys. Lett., 45, 693 (1999).



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