Franck–Condon Blockade in a Single-Molecule Transistor

Burzurí, Enrique; Yamamoto, Yoh; Warnock, Michael; Zhong, Xiaoliang; Park, Kyungwha; Cornia, Andrea; Zant, Herre S. J. van der

doi:10.1021/nl500524w

Cited by 114 publications

(139 citation statements)

References 30 publications

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“…The features of transport characteristics are determined by the occupation of the levels, the transition rates, and the Franck-Condon factors, rather than the level broadening. This is supported by experimental observation of dominant sequential tunneling 28,40 , and it was also theoretically shown in the case of without electron-vibron coupling 54 . In addition, the vibrational excitation energies of interest are larger than the experimental level broadening.…”

Section: Discussionsupporting

confidence: 78%

“…The previous DFT calculations suggest that the Fe 4 has only three vibrational modes with the electron-vibron coupling greater than unity 28 .…”

Section: Introductionmentioning

confidence: 93%

“…The neutral Fe 4 has the total ground-state spin S = 5 with a magnetic anisotropy barrier of 16.2 K [ Fig. 1(b)] 28,40,41 , while its doubly degenerate excited spin multiplets S = 4 are located at 4.8 meV above the ground-state spin multiplet S = 5 41 .…”

Section: Introductionmentioning

confidence: 99%

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Electron-vibron coupling effects on electron transport via a single-molecule magnet

et al. 2015

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We investigate how the electron-vibron coupling influences electron transport via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM) Fe 4 , by using a model Hamiltonian with parameter values obtained from density-functional theory (DFT). Magnetic anisotropy parameters, vibrational energies, and electron-vibron coupling strengths of the Fe 4 are computed using DFT. A giant spin model is applied to the Fe 4 with only two charge states, specifically a neutral state with the total spin S = 5 and a singly charged state with S = 9/2, which is consistent with our DFT result and experiments on Fe 4 single-molecule transistors. In sequential electron tunneling, we find that the magnetic anisotropy gives rise to new features in conductance peaks arising from vibrational excitations. In particular, the peak height shows a strong, unusual dependence on the direction as well as magnitude of applied B field. The magnetic anisotropy also introduces vibrational satellite peaks whose position and height are modified with the direction and magnitude of applied B field. Furthermore, when multiple vibrational modes with considerable electron-vibron coupling have energies close to one another, a low-bias current is suppressed, independently of gate voltage and applied B field, although that is not the case for a single mode with the similar electron-vibron coupling. In the former case, the conductance peaks reveal a stronger B-field dependence than in the latter case. The new features appear because the magnetic anisotropy barrier is of the same order of magnitude as the energies of vibrational modes with significant electron-vibron coupling. Our findings clearly show the interesting interplay between magnetic anisotropy and electron-vibron coupling in electron transport via the Fe 4 . The similar behavior can be observed in transport via other anisotropic magnetic molecules.

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Section: Discussionsupporting

confidence: 78%

“…The previous DFT calculations suggest that the Fe 4 has only three vibrational modes with the electron-vibron coupling greater than unity 28 .…”

Section: Introductionmentioning

confidence: 93%

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Electron-vibron coupling effects on electron transport via a single-molecule magnet

et al. 2015

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“…Electronic transport through the system requires the electron number to change and hence the polarons to be broken up, which is energetically disfavored if the electron-vibron coupling that holds them together is strong. This effect has been observed in single-molecule junctions 19 as well as in CNT systems, 12 adding to the variety of ways in which material structure can influence conductance. In addition, it has also been shown that the coupling between the mechanical and electronic degrees of freedom can be tailored to some extent.…”

Section: Introductionmentioning

confidence: 93%

Lifting the Franck-Condon blockade in driven quantum dots

et al. 2016

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Electron-vibron coupling in quantum dots can lead to a strong suppression of the average current in the sequential tunneling regime. This effect is known as Franck-Condon blockade and can be traced back to an overlap integral between vibron states with different electron numbers which becomes exponentially small for large electron-vibron coupling strength. Here, we investigate the effect of a time-dependent drive on this phenomenon, in particular the effect of an oscillatory gate voltage acting on the electronic dot level. We employ two different approaches: perturbation theory based on nonequilibrium Keldysh Green's functions and a master equation in Born-Markov approximation. In both cases, we find that the drive can lift the blockade by exciting vibrons. As a consequence, the relative change in average current grows exponentially with the drive strength.

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“…In addition, vibrational modes can couple to the charge carriers and therefore show up in conductance measurements. Figure 12(a) shows the dI/dV color plot of an Fe 4 junction in which vibrations appear as SET lines parallel to the diamond edges 39 . The measurements are performed at T = 1.8 K. The excitations can also be observed in the conductance plot in Figs.5(a) and 5(b).…”

Section: High-energy Excitations: Spin Excited Multipletsmentioning

confidence: 99%

Observing magnetic anisotropy in electronic transport through individual single-molecule magnets

Burzurí

Gaudenzi²,

Zant³

2015

J. Phys.: Condens. Matter

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We review different electron transport methods to probe the magnetic properties, such as the magnetic anisotropy, of an individual Fe4 SMM. The different approaches comprise first and higher order transport through the molecule. Gate spectroscopy, focusing on the charge degeneracy-point, is presented as a robust technique to quantify the longitudinal magnetic anisotropy of the SMM in different redox states. We provide statistics showing the robustness and reproducibility of the different methods. In addition, conductance measurements typically show high-energy excited states well beyond the ground spin multiplet of SMM. Some of these excitations have their origin in excited spin multiplets, others in vibrational modes of the molecule. The interplay between vibrations, charge and spin may yield a new approach for spin control.

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Franck–Condon Blockade in a Single-Molecule Transistor

Cited by 114 publications

References 30 publications

Electron-vibron coupling effects on electron transport via a single-molecule magnet

Electron-vibron coupling effects on electron transport via a single-molecule magnet

Lifting the Franck-Condon blockade in driven quantum dots

Observing magnetic anisotropy in electronic transport through individual single-molecule magnets

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