Quantum Conductance in Semimetallic Bismuth Nanocontacts

TL;DR

This study investigates the quantum conductance properties of bismuth nanocontacts at low temperatures, revealing atomic rearrangements, quantized conductance steps, and temperature-dependent charge carrier transitions.

Contribution

It provides new insights into the atomic-scale conductance behavior of bismuth nanocontacts and introduces a simple model for contact evolution at 77 K.

Findings

Observation of subquantum conductance steps indicating atomic rearrangements

Conductance histograms showing quantum peaks

Temperature-dependent transition from light to heavy charge carriers

Abstract

Electronic transport properties of bismuth nanocontacts are analyzed by means of a low temperature scanning tunneling microscope. The subquantum steps observed in the conductance versus elongation curves give evidence of atomic rearrangements in the contact. The underlying quantum nature of the conductance reveals itself through peaks in the conductance histograms. The shape of the conductance curves at 77 K is well described by a simple gliding mechanism for the contact evolution during elongation. The strikingly different behaviour at 4 K suggests a charge carrier transition from light to heavy ones as the contact cross section becomes sufficiently small.