CAN OHMIC SPIKES DEFINE QUANTUM-SYSTEMS

We investigate a system defined by an array of metallic spikes which e xtend down from an annealed Ni-AuGe metallisation deposited on the sur face of an AlGaAs/GaAs heterostructure. For the case where the spikes penetrate the two dimensional gas (2DEG), we show that electrons injec ted from the spikes into the 2DEG maintain phase coherence at low temp eratures, resulting in quantum interference processes determined by th e spike distribution. A unique device which induces a topological tran sition from a Corbino disc to a Hall bar is employed to explore this n ovel phenomenon. We discuss refinements to the spiking process which w ill facilitate the incorporation of these metallic spikes into nanostr ucture designs.