Single-Electron Transistors*

Mesoscopic devices like the single-electron transistor (SET) exhibit quantum behavior by forcing electrical current through a point-like constriction with quantized energy levels. Such devices typically require extreme nanofabrication techniques. Complex-oxide heterostructures such as the LaAlO₃/SrTiO₃ system support conductive interfaces that can be controlled using a reversible conductive-AFM lithography technique. These interfaces have richer properties than III-V or silicon-based systems, and support intrinsic magnetic, superconducting and structural phases. Here we describe renewed efforts to explore the properties of “sketched” SETs at the LaAlO₃/SrTiO₃ interface, focusing on the temperature and magnetic-field dependence of transport. We observe non-equilibrium conductances that cleanly resolve addition energies in nanoscale quantum dots, and track interactions between electronic states vs. experimental parameters such as gate voltage, temperature and magnetic field. These results yield new insights into intrinsic interactions between electrons confined within the quantum dot.