Special Condensed Matter Seminar

Dr. Blesson Sam Varghese

Title: "Strain engineering graphene and bilayer graphene transport properties"

Abstract : By mechanically distorting a crystal lattice, it is possible to engineer the electronic and optical properties of a material. Van der Waals materials are an ideal platform for strain engineering due to their excellent in-plane stiffness and mechanical flexibility. Predicted effects of external strain on graphene include changes in the magnitude and isotropy of Fermi velocity, shifts in the energy of Dirac cones, and shifts in the position of Dirac cones within the 2D Brillouin zone. Previous experiments have studied these effects on a local scale using STM and Kelvin probe force microscopy. With the in situ strain tuning capability developed in the lab, we investigate the effects of strain on quantum transport in graphene and bilayer graphene at cryogenic temperatures. Beyond straining, techniques to generate strain-induced electric fields and pseudo-magnetic fields by engineering strain gradients through device junction geometry are also explored in van der Waals material systems. Strain and strain gradients emerge as new control parameters in quantum transport experiments in van der Waals materials, alongside charge carrier density, electric fields, and magnetic fields.