Is there Ballistic Conductance Quantization in Real Life Metals Nanocontacts?

TL;DR

This paper critically examines the longstanding assumption that ballistic conductance quantization occurs in real metal nanocontacts, highlighting the significant role of lead resistance and questioning the universality of quantized conductance in practical metals.

Contribution

It challenges the traditional view by analyzing the impact of lead resistance and electron mean free path on conductance quantization in real metal nanocontacts.

Findings

Lead resistance is as significant as constriction resistance.

Mean free path limits the realization of ballistic transport.

Conductance quantization may not be observable in real metals.

Abstract

Theory and a vast set of experimental work in metals, since a century, appear to show that the mean free path of conduction electrons in a real metal is about the min (bulk mean free path, smallest transversal size of the metal), a result that was already proposed by J. J. Thomson in 1901. This establishes, as discussed in this work, serious difficulties to justify conductance quantization and ballistic transport in atomic/nanocontacts or nanoconstrictions of real life metals. The ohmic resistance of the leads proves to be as important as the ballistic one of the constriction.