Special Condensed Matter Seminar: "Real-space imaging of a nematic quantum liquid"

Fri, 01/13/2017 - 15:00 - 16:00
Ben Feldman, Princeton University

Electronic phases in condensed matter systems generally respect the symmetries of their solid state host. However, interactions among electrons can give rise to a variety of exotic correlated states characterized by broken symmetry. An intriguing example is the formation of electron fluids with wave functions that spontaneously break the symmetry of the underlying lattice. These phases are quantum analogues of classical liquid crystals and have recently attracted interest across disparate platforms ranging from high-temperature superconductors to two-dimensional electron systems. In this talk, I will describe scanning tunneling microscope measurements that provide a direct visualization of such a nematic quantum liquid on the surface of bismuth [1]. We perform spectroscopy of the quantum Hall states that arise at high magnetic field from anisotropic hole Fermi pockets on the Bi(111) surface. Our measurements reveal that a combination of strain and exchange interactions lift the Landau level (LL) degeneracy and produce valley-polarized states. We image the resulting anisotropic LL wave functions and show that they have a different orientation for each broken-symmetry state, providing a direct spatial signature of a nematic electronic phase.

[1] B. E. Feldman et al. Science 354, 316-321 (2016).

 

 

David Rittenhouse Laboratory, A4