Engineering:Electromigrated nanogaps

Electromigrated Nanogaps are gaps formed in metallic bridges formed by the process of electromigration.

Theory

A nanosized contact formed by electromigration acts like a waveguide for electrons. The nanocontact essentially acts like a one-dimensional wire with a conductance of [math]\displaystyle{ G =2e^2/h }[/math]. The current in a wire is the velocity of the electrons multiplied by the charge and number per unit length, [math]\displaystyle{ I = veN/L }[/math] or [math]\displaystyle{ G=veN/LV }[/math]. This gives a conductance of [math]\displaystyle{ G=ve^2N/LE }[/math]. In nano scale bridges the conductance falls in discrete steps of multiples of the quantum conductance [math]\displaystyle{ G =2e^2/h }[/math].

Uses

• Electromigrated Nanogaps have shown great promise as electrodes in use in molecular scale electronics.
• Researcher have used feedback controlled electromigration to investigate the magnetoresistance of a quantum spin valve.