Fractional Conductance in Hydrogen-Embedded Gold Nanowires

Abstract

Interaction of the physically adsorbed molecular hydrogen with a breaking gold nanowire results in additional stable atomic configurations in few atom contacts and appearance of fractional peaks in the conductance histogram. This effect is explained by peculiar dynamic evolution of the hydrogen-embedded nanoconstriction due to competition between tensile and capillary forces. Dimerization within the atomic wire and hydrogen-assisted stabilization of gold dimers results in preferable atomic arrangements with conductivity close to 0.5 and 1.5 of quantum conductance unit G(0)=2e(2)/h.

Conductance bistability of gold nanowires at room temperature

“…3,4 While quantized conductance behavior of the gold nanowire with the ideal unit of G 0 seems to be well established in certain cases, the appearance of abnormal fractional conductance in the gold nanowire has recently attracted much attention. [5][6][7][8][9][10][11][12][13][14][15] Several models such as spin polarized conductance, 5,6 structural deformation, [7][8][9][10] scattering on impurities and defects, [11][12][13] and change in the electronic states 14,15 have been proposed to explain the behavior of fractional conductance. These models assume that the origins of fractional conductance are deviation of the one-dimensional ͑1D͒ monoatomic wire from the ideal structure and the possible contribution of Peierls transition.…”

“…These models assume that the origins of fractional conductance are deviation of the one-dimensional ͑1D͒ monoatomic wire from the ideal structure and the possible contribution of Peierls transition. 7 If one can assume the formation of the gold monoatomic wire, the structural transition between bistable states with distinct values of conductance, e.g., Peierls transition, can also contribute to well-defined fractional values at the conductance quantization. Although the origin of the fractional conductance has not been clarified yet, it seems to be very important to control the quantized behavior of 1D materials by external perturbation, especially for the control of the reversible transition between the two states ͑1G 0 and fractional conductance͒.…”

Atomic and Electronic Structures and Properties of Nanomaterials on Metal Substrates

“…Furthermore, fractional conductance feature and reversible conductance fluctuation between 1G 0 and fractional conductance were reported for the gold nanowires under hydrogen dosing at 20 K in UHV. 53 If the dimerization is the origin of the fractional conductance, we could observe the Peierls transition of the 1D metal (monoatomic wire) at room temperature.…”

“…The specific structure with 0.5-0.7G 0 (fractional wire) became more stable than the structure with 1G 0 (normal wire). It should be noted that the intensity of the fractional conductance feature does not exceed the 1G 0 peak intensity even in the system in UHV at 20 K, 53 that is, fractional wire cannot be kept as the most energetically favorable structure. The present observation proved that structural bistability of gold monoatomic wires could be tuned by changing the electrochemical potential.…”

Metal atomic contacts under defined environmental conditions

“…Single hydrogen molecular junctions are fabricated by breaking the Pt atomic contacts in a hydrogen atmosphere [12,13]. The formation of a single hydrogen molecular junction was reported for Au and Cu atomic contacts [14][15][16][17]. The interaction between metal atomic contacts and molecules has been investigated at low temperatures in detail, using conductance, vibration spectroscopy, shot noise, and other techniques.…”