Size dependent breakdown of superconductivity in ultranarrow nanowires.

Below a certain temperature T(c) (typically cryogenic), some materials lose their electric resistance R entering a superconducting state. Following the general trend toward a large scale integration of a greater number of electronic components, it is desirable to use superconducting elements in order to minimize heat dissipation. It is expected that the basic property of a superconductor, i.e., dissipationless electric current, will be preserved at reduced scales required by modern nanoelectronics. Unfortunately, there are indications that for a certain critical size limit of the order of approximately 10 nm, below which a "superconducting" nanowire is no longer a superconductor in a sense that it acquires a finite resistance even at temperatures close to absolute zero. In the present paper we report experimental evidence for a superconductivity breakdown in ultranarrow quasi-1D aluminum nanowires.