Elektroneninjektion in kontaktierte Quantendrähte
Final Report Abstract
We have studied a gated quantum wire contacted to source and drain electrodes in the Fabry-Perot regime. The wire is also coupled to a third terminal (tip), and we have allowed for an asymmetry of the tip tunneling amplitudes of right and left moving electrons. We have analyzed configurations where the tip acts as an electron-injector or as a voltage-probe, and have shown that the transport properties ofthis three-terminal setup exhibit very rich physical behavior. For a non-interacting wire we have found that a tip in the voltage-probe configuration affects the source-drain transport in different ways, namely by suppressing the conductance, by modulating the Fabry-Perot oscillations, and by reducing their visibility. The combined effect of electron-electron interaction and finite length of the wire, accounted for by the inhomogeneous Luttinger liquid model, leads to significantly modified predictions as compared to models based on infinite wires. We have shown that when the tip injects electrons asymmetrically the charge fractionalization induced by interaction cannot be inferred from the asymmetry of the currents flowing in source and drain. Nevertheless, interaction effects are visible as oscillations in the non-linear tip-source and tip-drain conductances. We have shown that important differences with respect to a two-terminal setup emerge, suggesting new strategies for the experimental investigation of Luttinger liquid behavior. We have applied the approach to study intratube quantum dots realized In metallic single-walled carbon nanotubes by local defects created by means of low dose medium energy Ar+ irradiation. Particle-in-a-box-like states have been observed with level spacing up to 200 meV much larger than the thermal broadening at room temperature. By means of Fourier-transform scanning tunneling spectroscopy compared to results of our model we have shown clear signatures for inter- and intra-valley scattering of electrons confined between consecutive defects. Effects arising from lifting the degeneracy of the Dirac cones within the first Brillouin zone have been also observed.
Publications
- Electron scattering in intra-nanotube quantum dots. Phys. Rev. Lett. 102, 245505 (2009)
G. Buchs, D. Bercioux, P. Ruffieux, P. Gröning, H. Grabert, and O. Gröning
- Electron tunneling into a quantum wire in the Fabry-Perot regime. Phys. Rev. 8 79, 035121 (2009)
S. Pugnetti, F. Dolcini, D. Bercioux, and H. Grabert
