Subquantum conductance steps in atom-sized contacts of the semimetal Sb

Abstract
The transition from semimetallic Sb contacts to vacuum tunnel junctions is studied using a mechanically controllable break junction. The conductance of an atom-sized contact is shown to be small compared to the quantum unit due to the large Fermi wavelength of the electrons in Sb. Observation of subquantum conductance steps when varying the contact area of atomic dimensions gives clear experimental evidence for rearrangements of atoms building up the contract.