Conductance oscillations in metallic nanocontacts

Havu, P.; Torsti, T.; Puska, Martti J.; Nieminen, Risto M.

doi:10.1103/physrevb.66.075401

Cited by 43 publications

(59 citation statements)

References 21 publications

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“…A similar effect was found for other monovalent alkali-metal atoms such as Cs, but an opposite behavior, with a conductance bigger for even numbers of atoms than for odd numbers of atoms, was predicted for noble-metals (Cu, Ag and Au) [23]. The even-odd oscillation of the conductance for atomic wires of Na has also been analyzed using a pseudoatom-jellium model [19], where it was found that the sign of the effect is sensitive to the lead cone angle. Applying the first-principle recursion-transfer-matrix method Hirose at al.…”

supporting

confidence: 57%

“…4, 23 and even for a model in which D = d, this phase is in general, non-zero. Consequently, the even-odd behavior of the conductance strongly depends on the details of the coupling of the chain to the leads (through the phase shift Φ LR ) and this is the reason for the different predictions in the literature [4,10,12,18,19,23]. It is obvious from (1) that the conductance g becomes unity when the two leads are identical (r ′ L = r R ), and the cosine term is 1.…”

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confidence: 99%

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Nonuniversal behavior of the parity effect in monovalent atomic wires

et al. 2006

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We propose a mixed analytical-ab-initio method for the accurate calculation of the conductance in monovalent atomic wires. The method relies on the most general formula for ballistic transport through a monovalent wire, whose parameters can be determined from first-principles calculations. Our central result is the demonstration of the highly non-universal behavior of the conductance, which depends on the fine details of the contacts to the leads. We are therefore able to reconcile a large number of the apparently contradictory results that have recently appeared in the literature. 73.63.Rt,73.40.Cg In the last two decades transport properties of atomic contacts have been the subject of intensive research (for overviews see Ruitenbeek [1] and Agraït, Yeyati and Ruitenbeek [2]). First experimental evidences of the formation of golden atomic chains have been reported by Yanson et al. and Ohnishi et al. [3]. Experiments on chains of Au, Pt and Ir atoms [4] exhibit electrical conductance oscillations as a function of the wire length and similar oscillations as a function of bias voltage and electrode separation [5,6]. Rodrigues et al. [7] investigated the energetically preferred orientation of the crystal planes of the wire by the application of highresolution transmission electron microscopy. Their results show a strong correlation between the atomic arrangement and the conductance.The above experiments were stimulated by early theoretical predictions of conductance quantization [8] and conductance oscillations [9,10]. The latter issue generated a sequence of theoretical papers using a variety of techniques [11,12,13,14,15,16,17,18,19,20,21,22,23]. Density-functional theory predicted that the conductance of Na atom chains is close to the conductance quantum 2e 2 /h for odd numbers of atoms, and smaller than this for even numbers of atoms [10,15,16,20]. In the literature this is called the even-odd effect. A similar effect was found for other monovalent alkali-metal atoms such as Cs, but an opposite behavior, with a conductance bigger for even numbers of atoms than for odd numbers of atoms, was predicted for noble-metals (Cu, Ag and Au) [23]. The even-odd oscillation of the conductance for atomic wires of Na has also been analyzed using a pseudoatom-jellium model [19], where it was found that the sign of the effect is sensitive to the lead cone angle. Applying the first-principle recursion-transfer-matrix method Hirose at al. [22] showed that the bonding nature of the atoms at the contact plays a crucial role in determining transport properties. Lee and Kim[17] and Zeng and Claro [18], studied the effects of symmetries and found that the conductance of atomic chains with mirror symmetry and an odd number of atoms is always equal to the conductance quantum 2e 2 /h.In the literature various heuristic models have been proposed to interpret physically the results mentioned above: the standing wave model proposed by Emberly et al. [12], a simple barrier model suggested by Lee et al. [23], a simplified one-dimension...

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confidence: 57%

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confidence: 99%

Nonuniversal behavior of the parity effect in monovalent atomic wires

et al. 2006

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“…44, we do not see a strong lead-shape dependence in the conductance. The widening of the cone angle lowers the conductance as the edges of the wire become sharper.…”

Section: A Atomic Wirementioning

confidence: 82%

Finite-element implementation for electron transport in nanostructures

Havu¹,

Havu²,

Puska³

et al. 2006

The Journal of Chemical Physics

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Articles you may be interested inDeriving k·p parameters from full-Brillouin-zone descriptions: A finite-element envelope function model for quantum-confined wurtzite nanostructures J. Appl. Phys. 116, 033709 (2014) We have modeled transport properties of nanostructures using Green's-function method within the framework of the density-functional theory. The scheme is computationally demanding, so numerical methods have to be chosen carefully. A typical solution to the numerical burden is to use a special basis-function set, which is tailored to the problem in question, for example, the atomic-orbital basis. In this paper we present our solution to the problem. We have used the finite-element method with a hierarchical high-order polynomial basis, the so-called p elements. This method allows the discretation error to be controlled in a systematic way. The p elements work so efficiently that they can be used to solve interesting nanosystems described by nonlocal pseudopotentials. We demonstrate the potential of the implementation with two different systems. As a test system a simple Na-atom chain between two leads is modeled and the results are compared with several previous calculations. Secondly, we consider a thin hafnium dioxide ͑HfO 2 ͒ layer on a silicon surface as a model for a gate structure of the next generation of microelectronics.

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“…Here, it should be noted that the deviation of the conductance from the quantized value itself is not surprising. Conductances of atomic chains and atomic point contacts have been found to be sensitive to their structures and interface geometries, as shown by a few theoretical studies [13,14,33] and indicated by the experimental fact that the peaks of the conductance histogram of the atomic point contacts at the quantized values are not very sharp. It is also worth mentioning that dissipation processes in atomic chains, such as the excitation of the atomic vibrations by the electrons traversing the chain [34], have not been considered in our calculation.…”

Section: Effects Of Relaxation On Currentsmentioning

confidence: 97%

Ab initio calculation of stable structures of a Na atomic chain under bias voltages

Gohda

Furuya

et al. 2003

Science and Technology of Advanced Materials

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The stable geometries of a three-atom Na chain connected to two semi-infinite jellium electrodes are studied under bias voltages by performing ab initio force calculations within the density functional theory. At a low bias voltage of 0.01 V, the stable geometry is found to be symmetric, while it becomes asymmetric for higher bias voltages. The displacements of Na atoms in the chain are proportional to the applied bias voltages up to 1 V, while their behavior changes drastically above 1 V. These results can be understood from the behavior of charges induced by the applied voltage. It is also found that the structural relaxation due to the bias voltage also affects the potential drop along the chain and the current-voltage characteristics of the chain. q

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Conductance oscillations in metallic nanocontacts

Cited by 43 publications

References 21 publications

Nonuniversal behavior of the parity effect in monovalent atomic wires

Nonuniversal behavior of the parity effect in monovalent atomic wires

Finite-element implementation for electron transport in nanostructures

Ab initio calculation of stable structures of a Na atomic chain under bias voltages

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