Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:

WTe2 is a layered semimetal that can be exfoliated down to a monolayer like graphite, but in many ways it is very different from graphite, having strong spin-orbit coupling and low symmetry. When undoped, thin WTe2 becomes insulating at low temperatures even though the band structure is calculated to remain metallic. In monolayer WTe2 the insulating state is topologically nontrivial, supporting helical boundary modes, it has peculiar transport characteristics, and it undergoes a transition to a gate-tuneable superconducting state at a small level of electron doping. Using new ultra-high quality crystals, we have been investigating the properties of the insulating, metallic and superconducting states, with the hypothesis in mind that the insulating state results from exciton formation and condensation in equilibrium, and that the superconductor is unconventional. I will report on the state of our knowledge.

More about the Speaker:

David Cobden is a Professor of Physics at the University of Washington and Director of the Thouless Institute for Quantum Matter. His PhD is from Cambridge University, MSc from University of St. Andrews, and BA from Oxford. The Cobden Group aims to study new physics in nanowires, nanotubes, and two-dimensional materials, with particular interests in low-dimensional, topological and many-body effects and phase transitions. We fabricate a variety of nanoscale device structures and measure their properties using combinations of electrical transport, optics, scanning probes, photoemission, and other techniques.