Richard L. Greene Dissertation Award in Experimental Condensed Matter or Materials Physics: Imaging electronic wavefunctions and interactions on the surface of bismuth

Quantum materials provide a rich platform for realizing novel phenomena that can emerge from a confluence of electronic interactions, symmetry breaking and topology. In this talk, I will discuss scanning tunneling microscope experiments that explore the role of electron-electron interactions and their tunability on the surface of bismuth. In the presence of an applied magnetic field, the bismuth surface states enter the quantum Hall regime, in which our spectroscopic measurements reveal a number of exotic ordered ground states. Specifically, we observe a nematic phase with broken rotational symmetry and a ferroelectric phase that carries a dipole moment. We use the scanning tunneling microscope to directly visualize the wavefunctions of these broken symmetry phases. Furthermore, we image local nematic domains and find counter-propagating one-dimensional quantum Hall edge modes at their boundaries. We can change the number of edge modes at the domain walls to realize strikingly different regimes where the boundary is either metallic or insulating, in accordance with theory for a new class of interacting Luttinger liquids.
This talk presents work done during my Ph.D. in Ali Yazdani’s lab at Princeton University.