Speaker: Jedediah Pixley (Rutgers)

Host: Tom Iadecola

Title: Twisting and stacking two-dimensional quantum materials

Abstract: The ability to control and manipulate the strength of correlations in quantum matter is one of the central questions in condensed matter physics today. While pressure, chemical doping, or magnetic field have served as conventional tuning knobs for a wide class of correlated systems, the ability to twist van der Waals materials has recently emerged as a novel scheme to engineer strong correlations and tune electronic properties. For example, when two sheets of graphene are twisted to a "magic angle," the kinetic energy of the electronic degrees of freedom vanishes and, as a result, interaction effects dominate. This has now been demonstrated experimentally following the recent discovery of superconductivity in close proximity to correlated insulating phases in magic-angle graphene. 

In this talk, I will demonstrate how twisting and stacking two-dimensional materials is now possible in a wide range of van der Waals materials. First, we will discuss experiments that align twisted bilayer graphene with the hexagonal boron nitride substrate, whose relaxational properties lead to the formation of quasicrystalline moire heterostructures. We will then discuss placing two distinct transition metal dichalcogenides on top of each other (namely MoTe2/WSe2) to realize an effective heavy fermi liquid with a topological character. Last, we will demonstrate how unconventional superconductors can be manipulated via a twist. These results will then be applied to describe recent experiments on twisted slabs of the high-temperature superconductor Bi₂Sr₂CaCu₂O_8+y.

Jed Pixley is an Associate Professor of Physics and Astronomy at Rutgers, the State University of New Jersey. Jed received his PhD at Rice University in 2014. Prior to joining Rutgers, he was a postdoctoral fellow at the Condensed Matter Theory Center of the University of Maryland. Jed’s research focuses on the discovery, characterization, and prediction of correlated quantum phases of matter as well as the intriguing phase transitions among them.