Quantized conductance in Au-Pd and Au-Ag alloy nanocontacts

Enomoto, Akihiro; Kurokawa, Shu; Sakai, Akira

doi:10.1103/physrevb.65.125410

Cited by 69 publications

(49 citation statements)

References 33 publications

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“…Systems of this type can be realized experimentally by using alloys to fabricate the point contacts. 19,20 According to our preliminary study, 21 we await the variation of conductance depending on the atomic number of the impurity situated at the central site. The number of conducting modes is also expected to change with respect to the atomic number of the impurity, especially because of the existence of the virtual bound states.…”

Section: Introductionmentioning

confidence: 99%

Ab initioapproach to the ballistic transport through single atoms

2006

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We present a systematic study of the ballistic electron conductance through sp and 3d transition metal atoms attached to copper and palladium crystalline electrodes. We employ the ab initio screened Korringa-Kohn-Rostoker Green's function method to calculate the electronic structure of nanocontacts while the ballistic transmission and conductance eigenchannels were obtained by means of the Kubo approach as formulated by Baranger and Stone. We demonstrate that the conductance of the systems is mainly determined by the electronic properties of the atom bridging the macroscopic leads. We classify the conducting eigenchannels according to the atomic orbitals of the contact atom and the irreducible representations of the symmetry point group of the system that leads to the microscopic understanding of the conductance. We show that if impurity resonances in the density of states of the contact atom appear at the Fermi energy, additional channels of appropriate symmetry could open. On the other hand the transmission of the existing channels could be blocked by impurity scattering.

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Section: Introductionmentioning

confidence: 99%

Ab initioapproach to the ballistic transport through single atoms

2006

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“…We have already studied conductance quantization of a Pd nanowire in solution [8]. The conductance histogram displayed a clear feature peak at 1 G 0 , while conductance quantization was not observed in UHV at room temperature [11]. At low temperatures in UHV, the appearance of the 1 G 0 and 0.5 G 0 features were reported in the conductance histogram for Pd under hydrogen dosing [12].…”

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confidence: 99%

Fabrication of stable Pd nanowire assisted by hydrogen in solution

Kiguchi

Murakoshi

2006

Applied Physics Letters

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We have mechanically fabricated a Pd nanowire in solution under electrochemical potential control. A clear feature appeared in the conductance histogram when the electrochemical potential of the Pd wire was kept at the hydrogen evolution potential. Conductance traces showed the Pd wire was stretched 0.4 nm in length just before breaking, suggesting that at least two Pd atoms might contribute to the formation of the Pd wire. The results indicate that a certain atomic configuration of the Pd nanowire is stabilized by hydrogen. We discuss the stabilization mechanism due to changes in bond strengths caused by hydrogen adsorption or incorporation.Fabrication and characterization of metal atomic wires have attracted attention due to their potential applications in future electronic devices [1]. Recently, Ir, Pt, Au mono atomic wires have been fabricated by pulling nano contacts using a scanning tunneling microscope (STM) or a mechanically controllable break junction (MCBJ) in ultra high vacuum (UHV) at low temperatures [1][2][3]. In addition to methods in UHV, the electrochemical method has been recognized as another powerful approach in the fabrication of metal nanowires [4][5][6][7][8]. Recently, we have demonstrated that Fe, Co, and Ni metal nanowires were stabilized in solution at room temperature via the hydrogen evolution reaction [6,7]. Furthermore, we observed results suggesting the formation of a mono atomic Ni wire in solution, while mono atomic wires of 3d and 4d metals have not been prepared in UHV up to now.In the present study, we have studied the hydrogen assisted stabilization of the Pd (4d metal) nanowire in the fabrication of a mono atomic wire. A mono atomic Pd wire is predicted to be ferromagnetic [9], and to test this hypothesis it is useful to fabricate this wire. In addition to the stabilization of the Pd nanowire by hydrogen, the interaction between hydrogen and the Pd nanowire should be interesting. Since the interaction between hydrogen and Pd is large, the nanowire of the palladium hydride formed in solution should have electrical properties [10].In our study of the Pd nanowire, we have chosen to measure the conductance. Electrical conductance through a metal nanowire on an atomic scale is expressed by G = 2e 2 /h T i where T i is the transmission probability of the i-th conductance channel, e is the electron charge, and h is Plank's constant [1]. Since conductance quantization depends on the atomic structure of a nanowire and the inherent properties of metals, we can study the atomic and electronic structures of metal nanowires by the conductance measurements. We have already studied conductance quantization of a Pd nanowire in solution [8]. The conductance histogram displayed a clear feature peak at 1 G 0 , while conductance quantization was not observed in UHV at room temperature [11]. At low temperatures in UHV, the appearance of the 1 G 0 and 0.5 G 0 features were reported in the conductance histogram for Pd under hydrogen dosing [12]. At the present stage, it is clear that hydrogen sta...

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“…This is, however, not the case of alloy single-atom contacts. The single-atom conductance of Au and Cu, for example, shows no substantial changes with the addition of Pd and Ni, respectively, up to a concentration as high as 50 at% (Bakker et al, 2002;Enomoto et al, 2002). In the conductance histogram of AuPd and CuNi alloys, the single-atom peak of Au and Cu remains at 1G 0 and stays unshifted with alloying, though its intensity decreases nearly linearly with increasing the solute concentration.…”

Section: Break Voltage Of Alloy Contactsmentioning

confidence: 99%