Highly Stable Deterministically Configurable Metal Quantum Point Contacts (MQPCs)
I. Yutsis, N. Ittah, Y. Selzer
Tel Aviv University, IL
Keywords: quantum point contact, Electromigration, break junction
Abstract:Metal quantum point contacts1 (MQPCs) with dimensions comparable to the de Broglie wavelength of conducting electrons, reveal ballistic transport of electrons and quantized conductance in units of G0=2e2/h~13k. While these contacts hold great promise for applications such as coherent controlled devices and atomic switches their realization is mainly based on the scanning tunneling microscope (STM) and mechanically controlled break junction (MCBJ), which cannot be integrated into electronic circuits. MQPCs produced by these techniques have also limited stability at room temperature. We present a new method to form gold MQPCs with quantized conductance values in the range of 1-4G0. The atomic contacts appear to be stable at room temperature for hours and can be deterministically switched between conductance values, or reform in case they break, using voltage pulses. The method enables to integrate MQPCs within nano-scale circuits to fully harness their unique advantages. We also demonstrate the effect of laser light on the conductance of the contacts. The results are in par with theoretical calculations, demonstrating the role of the electronic structure of the leads on photoassisted transport through MQPCs.