Speaker
Apply to be<br> considered for a student <br> award (Yes / No)?
Yes
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
MSc
Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?
Yes
Main supervisor (name and email)<br>and his / her institution
Prof. BOTHA, Andre Erasmus (UNISA), Bothaae@unisa.ac.za
Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)
Yes
Abstract content <br> (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>
The ability to probe interactions at the atomic level via scanning tunneling microscopy and other techniques has led to great interest in contact formation between atomic-sized metal electrodes [Agrait N et al. 2003 Phys. Rep. 377 81]. For example, achieving ever smaller electronic circuit sizes is still a very important practical goal of nanotechnology [Lu Y et al. 2010 Nature Nanotechnology 5 218]. In the present work, it is demonstrated by two complementary simulation techniques that atomic-sized gold surfaces can be sharpened reproducibly, or mechanically annealed, until they are stable and no longer change. Experimentally, stable sharp gold tips may be achieved by repeatedly indenting into a surface with the tip of a scanning tunneling microscope. Such a process can be simulated by classical molecular dynamics (CMD), which describes the dynamics of the gold atoms as the two atomic-sized surfaces make and break contact [Sabater C et al. 2012 Phys. Rev. Lett. 108 205502]. To account for the interactions between the atoms in simulations, semi-empirical potentials fitted to various material parameters of the metals are used. The second simulation method, density functional theory (DFT) transport calculations [Palacios J J et al. 2002 Phys. Rev. B 66 035322], serves to obtain the electronic properties of the CMD-simulated system, such as the transmission across the electrodes when they first make contact. This paper presents the CMD results of the repeated indentation of a gold tip into a flat gold surface, with and without adatoms on the surface beneath the tip. The quantized conductances of a large number of CMD snapshot configurations of these surfaces, at various points during the process of contact formation, are also presented. These results permit a better understanding and interpretation of the experimental observations.
