Shot noise variation within ensembles of gold atomic break junctions at room temperature

Chen, Ruoyu; Matt, Manuel; Pauly, Fabian; Nielaba, Peter; Cuevas, Juan Carlos; Natelson, Douglas

doi:10.1088/0953-8984/26/47/474204

Cited by 17 publications

(20 citation statements)

References 66 publications

(120 reference statements)

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“…As a self-consistency check, τ 2 and τ 3 are indeed small below 1 G 0 and 2 G 0 respectively. Simulations in a previous paper [49] based on molecular dynamics and the Green functions technique match these observations. At 4 K such a simulation predicted an enhancement of the ensemble-averaged Fano factors close to 0.5 G 0 , as a result of maximized τ 2 contribution; This is reproduced by the transmittance mapping extracted from the data.…”

Section: Resultssupporting

confidence: 61%

Evolution of shot noise in suspended lithographic gold break junctions with bias and temperature

Chen¹,

Natelson²

2016

Nanotechnology

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Shot noise is a powerful tool to probe correlations and microscopic transport details that conductance measurements alone cannot reveal. Even in atomic-scale Au devices that are well described by Landauer-Büttiker physics, complications remain such as local heating and electron-phonon interactions. We report systematic rf measurements of shot noise in individual atomic-scale gold break junctions at multiple temperatures, with most bias voltages well above the energy of the Au optical phonon mode. Motivated by the previous experimental evidence that electron-phonon interactions can modify Fano factors and result in kinked features in bias dependence of shot noise, we find that the temperature dependence of shot noise from 4.2 to 100 K is minimal. Enhanced Fano factors near [Formula: see text] and features beyond simply linear bias dependence of shot noise near the [Formula: see text] plateau are observed. Both are believed to have non-interacting origins and the latter likely results from slightly bias-dependent transmittance of the dominant quantum channel.

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Section: Resultssupporting

confidence: 61%

Evolution of shot noise in suspended lithographic gold break junctions with bias and temperature

Chen¹,

Natelson²

2016

Nanotechnology

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“…We can again estimate it to be around 30%, as in the case of the clean surface. Moreover, due to SS contribution, missing in the supercell approach, the RSSE method provides much better quantized electron transport with the conductance of 1 G 0 (= 2e 2 /h) improving strongly an agreement with experimental data [53][54][55] .…”

supporting

confidence: 53%

Surface states and related quantum interference in \textit{ab initio} electron transport

Li,

Bertelsen,

Papior

et al. 2021

Preprint

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Shockley surface states (SS) have attracted much attention due to their role in various physical phenomena occurring at surfaces. It is also clear from experiments that they can play an important role in electron transport. However, accurate incorporation of surface states in ab initio quantum transport simulations remains still an unresolved problem. Here we go beyond the state-of-the-art non-equilibrium Green's function formalism through the evaluation of the self-energy in real-space, enabling electron transport without using artificial periodic in-plane conditions. We demonstrate the method on three representative examples based on Au(111): a clean surface, a metallic nanocontact, and a single-molecule junction. We show that SS can contribute more than 30% of the electron transport near the Fermi energy. A significant and robust transmission drop is observed at the SS band edge due to quantum interference in both metallic and molecular junctions, in good agreement with experimental measurements. The origin of this interference phenomenon is attributed to the coupling between bulk and SS transport channels and it is reproduced and understood by tight-binding model. Furthermore, our method predicts much better quantized conductance for metallic nanocontacts.

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“…For this purpose, we have employed the nonorthogonal Slater-Koster tight-binding parameterization of Refs. [94,95], which has been quite successful in determining a variety of properties of these atomic wires [8,11,69,[85][86][87] and it is known to accurately reproduce the band structure and total energy of bulk ferromagnetic materials [96]. In this parameterization one takes into account the relevant valence orbitals of the material under study.…”

Section: B Theoretical Approachmentioning

confidence: 99%

Orbital origin of the electrical conduction in ferromagnetic atomic-size contacts: Insights from shot noise measurements and theoretical simulations

et al. 2016

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With the goal to elucidate the nature of spin-dependent electronic transport in ferromagnetic atomic contacts, we present here a combined experimental and theoretical study of the conductance and shot noise of metallic atomic contacts made of the 3d ferromagnetic materials Fe, Co, and Ni. For comparison, we also present the corresponding results for the noble metal Cu. Conductance and shot noise measurements, performed using a low-temperature break junction setup, show that in these ferromagnetic nanowires: (i) there is no conductance quantization of any kind, (ii) transport is dominated by several partially-open conduction channels, even in the case of single-atom contacts, and (iii) the Fano factor of large contacts saturates to values that clearly differs from those of monovalent (nonmagnetic) metals. We rationalize these observations with the help of a theoretical approach that combines molecular dynamics simulations to describe the junction formation with nonequilibrium Green's function techniques to compute the transport properties within the Landauer-Büttiker framework. Our theoretical approach successfully reproduces all the basic experimental results and it shows that all the observations can be traced back to the fact that the d bands of the minority-spin electrons play a fundamental role in the transport through ferromagnetic atomic-size contacts. These d bands give rise to partially open conduction channels for any contact size, which in turn lead naturally to the different observations described above. Thus, the transport picture for these nanoscale ferromagnetic wires that emerges from the ensemble of our results is clearly at variance with the well established conduction mechanism that governs the transport in macroscopic ferromagnetic wires, where the d bands are responsible for the magnetism but do not take part in the charge flow. These insights provide a fundamental framework for ferromagneticbased spintronics at the nanoscale.

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Shot noise variation within ensembles of gold atomic break junctions at room temperature

Cited by 17 publications

References 66 publications

Evolution of shot noise in suspended lithographic gold break junctions with bias and temperature

Evolution of shot noise in suspended lithographic gold break junctions with bias and temperature

Surface states and related quantum interference in \textit{ab initio} electron transport

Orbital origin of the electrical conduction in ferromagnetic atomic-size contacts: Insights from shot noise measurements and theoretical simulations

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