Improved conductance quantization in gold point contacts in high magnetic fields

We have studied the influence of magnetic field on room-temperature quantization in normal-metal point contacts by measuring the transient conductance during a mechanical break of the electric contact between two macroscopic pieces of Au. It is found that, with increasing the magnetic field parallel to the movement of a sharp tip retracted from a mechanical contact with a large Au plate, the conductance steps become increasingly better defined. We attribute this observation to a micro-mechanical force caused by magnetic field and acting on the atomic wires drawn by the tip at the final stages of the breaking process. (C) 2001 Elsevier Science B.V. All rights reserved.