Nonmonotonic Fano factor and backscattering effects in single-molecule junctions

Schultz, Maximilian G.

doi:10.1103/physrevb.82.195322

Cited by 12 publications

(24 citation statements)

References 30 publications

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“…Moreover, the experimental data present negative differential conductance features which go beyond the capability of the simple Anderson-Holstein model. Different extensions of this model [24][25][26][27] including asymmetric coupling or multiple electronic levels have been proposed to explain NDCs. In a recent work [18], they have been attributed to a spatial-dependent Franck-Condon factor, as it naturally occurs in a clamped nanotube, combined with the assumption of a vibron mode being mostly localized near one of the two dot ends.…”

Section: Introductionmentioning

confidence: 99%

Spectrum and Franck–Condon factors of interacting suspended single-wall carbon nanotubes

Donarini¹,

Abdullah²,

Grifoni³

2012

New J. Phys.

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A low-energy theory of suspended carbon nanotube quantum dots in weak tunnelling coupling with metallic leads is presented. The focus is on the dependence of the spectrum and the Franck-Condon factors on the geometry of the junction including several vibronic modes. The relative size and the relative position of the dot and its associated vibrons strongly influence the electromechanical properties of the system. A detailed analysis of the complete parameters space reveals different regimes: in the short vibron regime the tunnelling of an electron into the nanotube generates a plasmon-vibron excitation, whereas in the long vibron regime polaron excitations dominate the scenario. The small, position-dependent Franck-Condon couplings of the small vibron regime convert into uniform, large couplings in the long vibron regime. Selection rules for the excitations of the different plasmon-vibron modes via electronic tunnelling events are also derived.

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Section: Introductionmentioning

confidence: 99%

Spectrum and Franck–Condon factors of interacting suspended single-wall carbon nanotubes

Donarini¹,

Abdullah²,

Grifoni³

2012

New J. Phys.

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“…Interestingly, in this case the precession takes place in a higher dimensional space and is expected to be overlooked even more easily as compared to the simple case studied here. Scenarios can be envisaged in nuclear spin systems, [67] double QDs [68], or vibrating molecular devices [53,69,70]. Our simple example shows that, interestingly, Coulomb interactions realize both requirements (i) and (ii) while noncollinear spin valves naturally provide (iii).…”

Section: Discussionmentioning

confidence: 92%

Spin resonance without spin splitting

et al. 2015

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We predict that a single-level quantum dot without discernible splitting of its spin states develops a spin-precession resonance in charge transport when embedded into a spin valve. The resonance occurs in the generic situation of Coulomb blockaded transport with ferromagnetic leads whose polarizations deviate from perfect antiparallel alignment. The resonance appears when electrically tuning the interaction-induced exchange field perpendicular to one of the polarizations -- a simple condition relying on vectors in contrast to usual resonance conditions associated with energy splittings. The spin resonance can be detected by stationary dI/dV spectroscopy and by oscillations in the time-averaged current using a gate-pulsing scheme. The generic noncollinearity of the ferromagnets and junction asymmetry allow for an all-electric determination of the spin-injection asymmetry, the anisotropy of spin relaxation, and the magnitude of the exchange field. We also investigate the impact of a nearby superconductor on the resonance position. Our simplistic model turns out to be generic for a broad class of coherent few-level quantum systems.Comment: This is the version of the article published in Physical Review B in 201

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“…The second model, CON, shows constructive interference effects. Note that both systems have been extensively studied before [61,62,65,[70][71][72][73][74][75][76][77][78][79][80][81][82]. They are thus very useful to set the stage for the discussion of vibrationally induced decoherence, which is presented in the subsequent sections, Secs.…”

Section: A Basic Interference Effectsmentioning

confidence: 99%

Vibrationally induced decoherence in single-molecule junctions

2013

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We investigate the interplay of quantum interference effects and electronic-vibrational coupling in electron transport through single-molecule junctions, employing a nonequilibrium Green's function approach. Our findings show that inelastic processes lead, in general, to a quenching of quantum interference effects. This quenching is more pronounced for increasing bias voltages and levels of vibrational excitation. As a result of this vibrationally induced decoherence, vibrational signatures in the transport characteristics of a molecular contact may strongly deviate from a simple Franck-Condon picture. This includes signatures in both the resonant and the non-resonant transport regime. Moreover, it is shown that local cooling by electron-hole pair creation processes can influence the transport characteristics profoundly, giving rise to a significant temperature dependence of the electrical current. 85.65.+h,71.38.-k * Present address:

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Nonmonotonic Fano factor and backscattering effects in single-molecule junctions

Cited by 12 publications

References 30 publications

Spectrum and Franck–Condon factors of interacting suspended single-wall carbon nanotubes

Spectrum and Franck–Condon factors of interacting suspended single-wall carbon nanotubes

Spin resonance without spin splitting

Vibrationally induced decoherence in single-molecule junctions

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