Tien-Ming Chuang, Institute of Physics, Academia Sinica, Taiwan

"Direct Visualization of Electronic Liquid Crystal Phases in Correlated Topological Semimetals"

Abstract: Strongly correlated electron systems (SCESs), in which various order parameters compete or intertwine with each other, exhibit rich quantum states of matter. Topological materials, which host symmetry protected Dirac or Weyl fermions, however, are mostly weakly correlated. Hence, the search for correlated topological materials has attracted great attention. Here, we report a direct observation of the electronic liquid crystal phase in non‐symmorphic topological semimetals by using spectroscopic imaging ‐ scanning tunneling microscopy (SI‐STM). Our real-space SI‐STM images reveal electronic nanostructures of incommensurate stripe and intense local nematic order, which is reminiscent of the “checkerboard” pattern in underdoped cuprates. We further show the chemical substitution to the half‐filled square‐net layer plays a key role in the formation of electronic nematicity and stabilizes a unidirectional charge density wave instability towards incommensurate stripe order. Our quasiparticle scattering interference imaging also detects linearly dispersive q‐vectors, which are consistent with the calculated topological band structure. Our results demonstrate that these topological semimetals provide a fertile playground for the study of novel phenomena of correlated Dirac electrons, as well as highlight the importance of dopant atoms in the formation of stripe and nematic phases. Taken together, this opens a pathway towards further microscopic understanding of electronic liquid crystal phase in other SCESs, such as cuprates and iron pnictides.

If you would like to meet with Dr. Chuang, please contact Prof. de Lozanne (delozanne@physics.utexas.edu)