Colloquia and Events

Abstract for this week's colloquium (Thursday, Dec. 1, 3:05 - 4:20 pm):

Christopher Gutiérrez, UCLA, "Creating and visualizing symmetry-broken phases of matter in 2D materials"

Gas. Liquid. Solid. These are three phases of matter that we experience in our everyday lives. However, for electrons that live within solids, geometry and quantum mechanical effects can conspire to allow for the possibility of many more phases of matter. For instance, graphene — a single two-dimensional sheet of carbon atoms in a honeycomb lattice — has been predicted to host a plethora of new and interesting electronic phases. One such phase is called a density-wave, whereby electrons and the atomic lattice become unstable and together form a brand new crystal with a new symmetry. But amongst the many possible electronic phases, how does the system “choose” which one to display? And can one possibly control which macroscopic phase “wins”?

In this talk, I will describe our recent observations [Science Advances 8, eabm5180 (2022)] that an extremely small amount of surface defects can be used to purposely initiate the onset of a symmetrybreaking density wave phase in graphene. We detect the presence of this new phase using complementary photo-emission and diffraction techniques that measure the momentum of graphene’s electrons. Like an archaeologist re-assembling a dinosaur from its fossils, by measuring the kinetic energy and momentum of photo-emitted electrons, we can likewise piece together and visualize the symmetry and spectroscopic signature of this density wave phase in several graphene systems. Our results suggest a surprising sensitivity of the graphene lattice to even dilute surface disorder and open the door to harnessing adsorbed atoms for tailoring the properties of two-dimensional materials.

Physics and Astronomy Students: come enjoy a pizza lunch and meet our speaker! Rosser Hall 3rd floor patio (outdoors) next to the elevator. 12:30 – 1:30pm Thursday Dec 1st.

Fall 2022 Dept of Physics and Astronomy Colloquium Schedule

(will be updated throughout the semester)

            Thursdays 3:05pm – 4:20pm

             Zoom link:

  • Aug 25  No talk, first week of class
  • Sept 1  Meet & Greet in person, Bios159 followed by refreshments outdoors 
  • Sept 8  CANCELLED
  • Sept 15  Karine Le Bris, CSULA, atmospheric physics, "Determination of the radiative properties and detection of organofluorine compounds by mid-infrared spectroscopy"
  • Sept 22  Lizxandra Flores Rivera, MPIfA Heidelberg, astrophysics,  "Evolution of protoplanetary disks and planet formation"
  • Sept 29  David Van Buren,  JPL, "Medical Physics meets Aerospace Engineering in the Age of COVID:  the NASA Globally Accessible Ventilators"
  • Oct 6  Anna Nierenberg, UC Merced, "Revealing Dark Matter with Strongly Lensed Quasars"
  • Oct 13  Stephanie Meng Shen, CSU Fullerton, "The understanding and design of composite soft materials by computational simulations"
  • Oct 20  Fabien Florent Pinaud, USC, "Using single protein imaging microscopy to better understand diseases: applications to muscular dystrophies"
  • Oct 27  CANCELLED Giulia Palermo, UC Riverside, "Dynamics and mechanisms of CRISPR-Cas9 through the lens of computational methods"
  • Nov 3  Arianna Long, UT Austin, "Taming Giants: Studies on the Evolution of Massive Dusty Star-Forming Galaxies at High Redshifts"
  • Nov 10  Aisulu Aitbekova, Caltech, "Engineering catalytic materials for sustainable energy applications"
  • Nov 17  Virginie Faramaz,  U. Arizona, "From Icy Comet Belts to the Habitable Zone"
  • Nov 24  Thanksgiving Holiday
  • Dec 1  In person, Bios159, Christopher Gutiérrez, UCLA, "Creating and visualizing symmetry-broken phases of matter in 2D materials"
  • Dec 8   No talk, last week of class