Identification of vibration modes in single-molecule junctions by strong inelastic signals in noise

Tewari, Sumit; Sabater, C.; Ruitenbeek, J. M. van

doi:10.1039/c9nr05774a

Cited by 10 publications

(11 citation statements)

References 27 publications

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“…This was attributed to the opening of an otherwise closed d channel, along with the usual s channel, when exciting a transverse hindered rotation mode for the H 2 molecule. Recently, such a step-up has also been found in experiments (Tewari, Sabater, and van Ruitenbeek, 2019). As pointed out there, these steps in conductance are small and it is extremely difficult to distinguish them from the structures that could appear due to elastic scattering of electronic waves through defects in the Pt leads.…”

Section: H Iets and Sign Inversionmentioning

confidence: 89%

Advances and challenges in single-molecule electron transport

et al. 2020

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Electronic transport properties of single-molecule junctions have been widely measured by several techniques, including mechanically controllable break junctions, electromigration break junctions, and by means of scanning tunneling microscopes. In parallel, many theoretical tools have been developed and refined for describing such transport properties and for obtaining numerical predictions. Most prominent among these theoretical tools are those based upon density functional theory. In this review, theory and experiment are critically compared, and this confrontation leads to several important conclusions. The theoretically predicted trends nowadays reproduce the experimental findings well for series of molecules with a single well-defined control parameter, such as the length of the molecules. The quantitative agreement between theory and experiment usually is less convincing, however. Two main sources for the quantitative discrepancies can be identified. Experimentally, the atomic structure of the junction typically realized in the measurement is not well known, so simulations rely on plausible scenarios. In theory, correlation effects can be included only in approximations that are difficult to control for experimentally relevant situations. Therefore, one typically expects qualitative agreement with present modeling tools; in exceptional cases a quantitative agreement has already been achieved. For further progress, benchmark systems are required that are sufficiently well defined by experiment to allow quantitative testing of the approximation schemes underlying the theoretical modeling. Several key experiments can be identified suggesting that the present description may even be qualitatively incomplete in some cases. Such key experimental observations and their current models are also discussed here, leading to several suggestions for extensions of the models toward including dynamic image charges, electron correlations, and polaron formation.

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Section: H Iets and Sign Inversionmentioning

confidence: 89%

Advances and challenges in single-molecule electron transport

et al. 2020

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“…The majority of shot noise measurements for single-molecule junctions was carried out at low bias voltages, and they use S to extract information on elastic transmission coefficients, as mentioned above [11,12,16,18]. Only very recently the inelastic contributions to shot noise have been addressed experimentally in these kind of systems [56]. However, Ref.…”

Section: B Au-benzenedithiol-au Contactsmentioning

confidence: 99%

“…While shot noise in atomic contacts and molecular junctions has already been measured in the elastic lowbias regime [10-12, 17, 18, 26], the inelastic effects on electronic shot noise due to EV couplings have been analyzed only recently [20,[51][52][53][54][55][56]. Tsutsui et al [51] investigated the fluctuations of charge current flowing through a single molecule at T = 4 K. They report an increased noise signal at voltages that are characteristic for the molecular vibrational modes and find a similar peak structure in both shot noise and IET spectra.…”

Section: Introductionmentioning

confidence: 99%

“…Tsutsui et al [51] investigated the fluctuations of charge current flowing through a single molecule at T = 4 K. They report an increased noise signal at voltages that are characteristic for the molecular vibrational modes and find a similar peak structure in both shot noise and IET spectra. Tewari et al [56] recently demonstrated for deuterium molecules that the inelastic noise contributions due to vibrational excitations interacting with two-level fluctuators can be used to detect inelastic processes more precisely than with IET spectra. In the experimental work by Kumar et al [52] the shot noise of Au atomic contacts was measured at liquid helium temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Influence of electron-vibration interactions on electronic current noise of atomic and molecular junctions

Bahoosh¹,

Karimi²,

Belzig³

et al. 2019

Preprint

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We present an ab-initio method to simulate the current noise in the presence of electron-vibration interactions in atomic and molecular junctions at finite temperature. Using a combination of nonequilibrium Keldysh Green's function techniques and density functional theory, we study the elastic and inelastic contributions to electron current and shot noise within a wide range of transmission values in systems exhibiting multiple electronic levels and vibrational modes. Within our model we find the upper threshold, at which the inelastic noise contribution changes sign, at a total transmission between τ ≈ 0.90 and 0.95 for gold contacts. This is higher than predicted by the single-level Holstein model but in agreement with earlier experimental observations. We support our theoretical studies by noise measurements on single-atom gold contacts which confirm previous experiments but make use of a new setup with strongly reduced complexity of electronic circuitry. Furthermore, we identify 1,4-benzenedithiol connected to gold electrodes as a system to observe the lower sign change, which we predict at around τ ≈ 0.2. Finally, we discuss the influence of vibrational heating on the current noise.

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“…In the following years, shot noise was used to study various mesoscopic systems [3-6, 13, 15, 22-27]. Alongside mesoscopic measurements, molecules and atomic-scale structures have also been studied [28][29][30][31][32][33][34], mainly by means of mechanically controlled break junctions. More recently a few experimental groups demonstrated local shot noise measurements using a scanning tunneling microscope (STM) [7,8,14,17,[35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Shot-noise measurements of single-atom junctions

Tamir,

Caspari,

Rolf

et al. 2021

Preprint

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Current fluctuations related to the discreteness of charge passing through small constrictions are termed shot noise. This unavoidable noise provides both advantages -being a direct measurement of the transmitted particles' charge, and disadvantages -a main noise source in nanoscale devices operating at low temperature. While better understanding of shot noise is desired, the technical difficulties in measuring it result in relatively few experimental works, especially in single-atom structures. Here we describe a local shot-noise measurement apparatus, and demonstrate successful noise measurements through single-atom junctions. Our apparatus, based on a scanning tunneling microscope operates at liquid helium temperatures. It includes a broadband commercial amplifier mounted in close proximity to the tunnel junction, thus reducing both thermal noise and the input capacitance that limit traditional noise measurements. The full capabilities of the microscope are maintained in the modified system and a quick transition between different measurement modes is possible.

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Identification of vibration modes in single-molecule junctions by strong inelastic signals in noise

Abstract: Inelastic electron noise spectroscopy technique combining a high-bias shot noise with vibration-induced two level fluctuations.

Cited by 10 publications

References 27 publications

Advances and challenges in single-molecule electron transport

Advances and challenges in single-molecule electron transport

Influence of electron-vibration interactions on electronic current noise of atomic and molecular junctions

Shot-noise measurements of single-atom junctions

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