Physics

Dr. Nirat Ray
School of Physical Sciences, JNU

The prospect of designing novel materials with tailored electrical, optical, and magnetic properties has intrigued scientists and engineers for years. Building blocks for such “artificial solids” have emerged from recent advances in nanomaterial synthesis, lithography, and emerging understanding of their size-dependent properties. An important step to realizing the full potential of such nanostructured materials is to understand their nanoscale charge dynamics.  In the first part of my talk, I will focus on transport measurements in quantum dot arrays. Quantum dots (QDs) resulting from quantum confinement in all three spatial dimensions, are often thought of as artificial atoms with discrete charge and energy states. If one were to create a lattice of these artificial atom with sufficiently low disorder it would be possible to create an artificial solid with tunable properties. While transport studies in solution processed colloidal quantum dot assemblies reveal interesting non-poissonian noise statistics,  quantum dot arrays fabricated in GaAs using electron beam lithography and reactive ion etching to define the boundary of each dot show striking transition from a high resistance (low current) state to low resistance (high current) as a function of increasing source drain bias, indicative of collective phenomena occurring within these artificial quantum dot lattices. In the second part of my talk I will focus on transport studies in two other classes of designer solids: nanowire networks and artificial spin ice systems. I will conclude with a future outlook on the promise of artificial solids.