Conductance steps in point contacts: Quantization or cross-section jumps?

✍ Scribed by J.A. Torres; J.J. Sáenz

• Book ID: 103941188
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 262 KB
• Volume: 218
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(95)00602-8

✦ Synopsis

We present exact free-electron conductance calculations of narrow necks connecting two three-dimensional electron gases. A simple model for the evolution of an atomic point contact during an elongation process is proposed. The conductance and cross-section of the neck are calculated simultaneously during the elongation process. Our results present a qualitative behaviour which strikingly resemble the experimental results. We find that conductance discontinuities are always due to atomic rearrangements in the neck and, in general, do not correspond to a quantized value. Only the last conductance plateaus are close to a multiple of 2eZ/h, though the jumps themselves are still produced by atomic rearrangements. The exact shape of the last step depends on the type of material and is determined by quantum resonant scattering effects together with the elastic properties at the atomic scale.