Interface Geometry and Molecular Junction Conductance:  Geometric Fluctuation and Stochastic Switching

Basch, Harold; Cohen, Revital; Ratner, Mark A.

doi:10.1021/nl050702s

Cited by 243 publications

(256 citation statements)

References 102 publications

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“…During the formation of a Au-S covalent bond, multiple bonding scenarios exist depending on the location of the H atom, which could lead to drastic changes in the rupture force 44,52 , and a possibility of forming weaker coordinate bonds between the protonated SH groups and gold surfaces 53 . Recently, a comprehensive investigation on the elongation process of molecular junctions formed by octanedithiol molecule and Au electrodes indicated that the bonds that are easiest to break are the coordinated Au-linker contacts (B0.6 nN), which are smaller than the covalent thiolate-gold junctions (from B1.5 to B2.2 nN) 52 .…”

Section: Resultsmentioning

confidence: 99%

Quantifying thiol–gold interactions towards the efficient strength control

et al. 2014

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The strength of the thiol-gold interactions provides the basis to fabricate robust self-assembled monolayers for diverse applications. Investigation on the stability of thiol-gold interactions has thus become a hot topic. Here we use atomic force microscopy to quantify the stability of individual thiol-gold contacts formed both by isolated single thiols and in self-assembled monolayers on gold surface. Our results show that the oxidized gold surface can enhance greatly the stability of gold-thiol contacts. In addition, the shift of binding modes from a coordinate bond to a covalent bond with the change in environmental pH and interaction time has been observed experimentally. Furthermore, isolated thiol-gold contact is found to be more stable than that in self-assembled monolayers. Our findings revealed mechanisms to control the strength of thiol-gold contacts and will help guide the design of thiol-gold contacts for a variety of practical applications.

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Section: Resultsmentioning

confidence: 99%

Quantifying thiol–gold interactions towards the efficient strength control

et al. 2014

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“…[18][19][20][21][22][23][24] A thiol group is most commonly used to build a strong chemical link between the single molecules and the Au electrodes in molecular junctions. The conductance of such single-molecule junctions is typically several orders of magnitude smaller than G 0 =2e 2 / h ͑the conduc-tance quantum͒.…”

Section: Introductionmentioning

confidence: 99%

Effects of bonding type and interface geometry on coherent transport through the single-molecule magnetMn12

et al. 2010

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We examine theoretically coherent electron transport through the single-molecule magnet Mn 12 , bridged between Au͑111͒ electrodes, using the nonequilibrium Green's function method and the density-functional theory. We analyze the effects of bonding type, molecular orientation, and geometry relaxation on the electronic properties and charge and spin transport across the single-molecule junction. We consider nine interface geometries leading to five bonding mechanisms and two molecular orientations: ͑i͒ Au-C bonding, ͑ii͒ Au-Au bonding, ͑iii͒ Au-S bonding, ͑iv͒ Au-H bonding, and ͑v͒ physisorption via van der Waals forces. The two molecular orientations of Mn 12 correspond to the magnetic easy axis of the molecule aligned perpendicular ͓hereafter denoted as orientation ͑1͔͒ or parallel ͓orientation ͑2͔͒ to the direction of electron transport. We find that the electron transport is carried by the lowest unoccupied molecular orbital ͑LUMO͒ level in all the cases that we have simulated. Relaxation of the junction geometries mainly shifts the relevant occupied molecular levels toward the Fermi energy as well as slightly reduces the broadening of the LUMO level. As a result, the current slightly decreases at low bias voltage. Our calculations also show that placing the molecule in the orientation ͑1͒ broadens the LUMO level much more than in the orientation ͑2͒ due to the internal structure of the Mn 12 . Consequently, junctions with the former orientation yield a higher current than those with the latter. Among all of the bonding types considered, the Au-C bonding gives rise to the highest current ͑about one order of magnitude higher than the Au-S bonding͒, for a given distance between the electrodes. The current through the junction with other bonding types decreases in the order of Au-Au, Au-S, and Au-H. Importantly, the spin-filtering effect in all the nine geometries stays robust and their ratios of the majority-spin to the minorityspin transmission coefficients are in the range of 10 3 -10 8 . The general trend in transport among the different bonding types and molecular orientations obtained from this study may be applicable to other single-molecule magnets.

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“…Unfortunately, these comparisons are complicated by substantial variability in the measured values for the same molecule and signficant uncertainty about the atomic scale structure of the junction near the single molecule link [3]. Calculations are typically performed for relatively idealized junction structures and the conductance can be sensitive to the local geometry for widely used thiol linkages [16,17,18].…”

Section: Introductionmentioning

confidence: 99%

Electronic correlation in nanoscale junctions: Comparison of the GW approximation to a numerically exact solution of the single-impurity Anderson model

et al. 2008

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The impact of electronic correlation in nanoscale junctions, e.g. formed by single molecules, is analyzed using the single-impurity Anderson model. Numerically exact Quantum Monte Carlo calculations are performed to map out the orbital filling, linear response conductance and spectral function as a function of the Coulomb interaction strength and the impurity level position. These numerical results form a benchmark against which approximate, but more broadly applicable, approaches to include electronic correlation in transport can be compared. As an example, the self consistent GW approximation has been implemented for the Anderson model and the results compared to this benchmark. For weak coupling or for level positions such that the impurity is either nearly empty or nearly full, the GW approximation is found to be accurate. However, for intermediate or strong coupling, the GW approximation does not properly represent the impact of spin or charge fluctuations. Neither the spectral function nor the linear response conductance are accurately given across the Coulomb blockade plateau and well into the mixed valence regimes.

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Interface Geometry and Molecular Junction Conductance: Geometric Fluctuation and Stochastic Switching

Cited by 243 publications

References 102 publications

Quantifying thiol–gold interactions towards the efficient strength control

Quantifying thiol–gold interactions towards the efficient strength control

Effects of bonding type and interface geometry on coherent transport through the single-molecule magnetMn12

Electronic correlation in nanoscale junctions: Comparison of the GW approximation to a numerically exact solution of the single-impurity Anderson model

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