Open Access Nano Express

Understanding the structure of the first atomic contact in gold

Carlos Sabater1*, María José Caturla1, Juan José Palacios2 and Carlos Untiedt1

Author affiliations

1 Departmento de Física Aplicada, Universidad de Alicante, Carretera San Vicente del Raspeig, Alicante 03690, Spain

2 Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid 24105, Spain

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Citation and License

Nanoscale Research Letters 2013, 8:257  doi:10.1186/1556-276X-8-257

Published: 29 May 2013

Abstract

We have studied experimentally jump-to-contact (JC) and jump-out-of-contact (JOC) phenomena in gold electrodes. JC can be observed at first contact when two metals approach each other, while JOC occurs in the last contact before breaking. When the indentation depth between the electrodes is limited to a certain value of conductance, a highly reproducible behaviour in the evolution of the conductance can be obtained for hundreds of cycles of formation and rupture. Molecular dynamics simulations of this process show how the two metallic electrodes are shaped into tips of a well-defined crystallographic structure formed through a mechanical annealing mechanism. We report a detailed analysis of the atomic configurations obtained before contact and rupture of these stable structures and obtained their conductance using first-principles quantum transport calculations. These results help us understand the values of conductance obtained experimentally in the JC and JOC phenomena and improve our understanding of atomic-sized contacts and the evolution of their structural characteristics.

Keywords:
Electronic transport; Atomic size contacts; Mechanical annealing; Jump-to-contact phenomena; Jump-out-of-contact phenomena; Molecular dynamics simulations; Ab initio; DFT