The research of Faxian Xiu, assistant professor of electrical and computer engineering, and his first PhD student Nicholas Meyer attracted global attention when it was published in Scientific Reports, a primary research publication from the publishers of Nature.
As part of this research, Xiu and his team have grown high-quality topological insulator thin films on commercially available silicon substrates. The development of such a material could help eliminate loss in electrical power transmission, a task that has been pursued for many decades.
Topological insulators behave like electrical insulators in the bulk interior of a material, carrying a current along the material’s surface. It has been predicted that surface electrons in these insulators cannot be scattered by defects or non-magnetic impurities, so they produce little or no resistance as they travel.
Xiu and his team proposed measuring the amount of electrical charge stored in the material under the application of a time-varying electrical voltage to extract information regarding the electron transport on the topological surfaces. Their experiments demonstrated very strong oscillations in the conductivity of thin films under a varying magnetic field, suggesting that unique carrier transports do in fact exist on these surfaces.
Importantly, their method allows for the recognition of surface conduction at temperatures up to 60 K. This finding is a significant milestone because the interior of a material becomes more conducting as temperature increases, resulting in more obscured properties of surface conduction.
They are currently working on exploring different topological insulators and building new devices that can exploit the fact that the surface conduction produces very little electrical resistance. Their goal is to create electronics that run on and dissipate very little energy.
Their complete research is included in the paper “Quantum Capacitance in Topological Insulators,” which was published in Scientific Reports on September 18, 2012.
Xiu would like to acknowledge the financial support received from the National Science Foundation under the Award No. 1201883, and the College of Engineering at Iowa State University. The Microelectronics Research Center at Iowa State provided substantial equipment support during the project.