Robust Quantum Interference in Ultraclean Carbon Nanotubes and Other Stories

Abstract

I will talk about ongoing efforts in my lab at the University of Utah in one, two and three dimensional mesoscopic material systems.

In 1D, we study longer ultraclean carbon nanotubes than studied previously and observe new conductance oscillations versus gate voltage on top of the commonly observed Fabry-Perot conductance oscillations. These new oscillations are slower than the Fabry-Perot oscillations and up to an order of magnitude more robust in temperature, surviving up to 100K in our devices. Further using structurally characterized nanotubes, we find that the new oscillations are a fingerprint of the structure and allow identification of carbon nanotube chirality from a transport measurement for the first time.

In 2D, we study thermal transport in two-dimensional metal-organic graphene analogues and find promising thermoelectric figures of merit for potential application as thermoelectrics.

In 3D topological insulators (TIs), we create van der Waals heterostructures with boron nitride and top/bottom graphite gates for top/bottom surfaces of 3D TIs. Using these structures, we observe individually tunable half-integer quantum Hall effects in TI surfaces at lower magnetic fields than previous groups.

I will discuss implications of these measurements and other measurements we are performing on these systems in my lab.