Quantum Transport and Metallic Nanocohesion

University Of Arizona, Tucson AZ

Investigators

Abstract

This grant supports theoretical research on the cohesive and conducting properties of atomic-scale metal structures, with a particular emphasis on understanding the interrelation of electrical conduction and metallic cohesion. Motivation is provided by recent advances in scanning tunneling and atomic force microscopy, which have made it possible to fabricate and manipulate metallic structures atom by atom, as well as to measure the electrical and mechanical properties of spontaneously occuring atomic-scale structures. A phenomenon of fundamental interest is conductance quantization: it has been found that the electrical resistance of atomic-scale contacts formed in many metals is nearly equal to the resistance quantum h/e2 divided by an even integer. The mechanical analogue of conductance quantization has also been observed in gold nanocontacts: the cohesive force of the contact was found to exhibit quantum jumps on the scale of a nano-Newton, which were synchronized with the quantized steps in the resistance. A unified theoretical treatment of the cohesive and conducting properties of metallic nanostructures in terms of the electronic scattering matrix, which gave quantitative agreement with the experiments in gold, has been developed. The goal of the proposed research is to further elaborate this theoretical framework and to explore its implications for possible applications in nanomachines and nanoelectronics. %%% This grant supports theoretical research on the cohesive and conducting properties of atomic-scale metal structures, with a particular emphasis on understanding the interrelation of electrical conduction and metallic cohesion. Motivation is provided by recent advances in scanning tunneling and atomic force microscopy, which have made it possible to fabricate and manipulate metallic structures atom by atom, as well as to measure the electrical and mechanical properties of spontaneously occuring atomic-scale structures. A phenomenon of fundamental interest is conductance quantization: it has been found that the electrical resistance of atomic-scale contacts formed in many metals is nearly equal to the resistance quantum h/e2 divided by an even integer. The mechanical analogue of conductance quantization has also been observed in gold nanocontacts: the cohesive force of the contact was found to exhibit quantum jumps on the scale of a nano-Newton, which were synchronized with the quantized steps in the resistance. A unified theoretical treatment of the cohesive and conducting properties of metallic nanostructures in terms of the electronic scattering matrix, which gave quantitative agreement with the experiments in gold, has been developed. The goal of the proposed research is to further elaborate this theoretical framework and to explore its implications for possible applications in nanomachines and nanoelectronics. ***