Professor Bennett Goldberg Boston University "Strain Engineering of 2D Crystals" Thursday April 03, 2014 4:00pm PHYS 203 Refreshments are served at 3:30 p.m. in Physics room 242 Two-dimensional materials are flexible, transparent, compatible with living systems, and can enable new devices and physics based on their unique properties. One unique property is the ability of 2D crystals a single atom thick to undergo massive amounts of strain without failure. Since strain also drastically modifies the band structure leading to large changes in transport and optical properties, strain engineering of 2D crystals has the potential to create new devices, explore transport in pseudo-magnetic fields, and tune tunneling or excitonic effects. Graphene is the most well-studied of 2D crystals, and shows a strain-induced pseudo vector potential that can lead, in certain circumstances, to pseudo-magnetic fields. Recent work shows strain allows one to tune the band gap in transition metal dicalchognides, another class of 2D crystals. In this colloquium, we will explore strain by suspending 2D crystal membranes of graphene and hexagonal boron nitride over microchambers, creating a sealed drum. Tuning the strain through pressure deflects the membrane, changing its properties. Remarkably, the assumption of a fixed circumference is wrong, because we observe the 2D crystal sliding across the supported part of the microchamber. We will discuss friction, strain engineering, and future prospects for 2D crystals. Jaime Turner Birck Nanotechnology Center 1205 West State Street West Lafayette, IN 47907-2057 Email: jjturner@purdue.edu<mailto:jjturner@purdue.edu> Phone: 765-494-3509