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Xiaomeng Liu, Princeton University

Condensed Matter Seminar - "More layers are different: designing quantum matter with assembled heterostructures"

Event Type
Physics - Condensed Matter
ESB 190
Feb 10, 2023   1:00 pm  
Xiaomeng Liu, Princeton University
Stephen Bullwinkel
Originating Calendar
Physics - Condensed Matter Seminar

From superconductivity to fractionalized particles, fascinating phenomena arise in quantum materials due to the collective behaviors of electrons. These quantum effects challenge our understanding of nature and open up new possibilities for future technologies in quantum information. In my talk, I will discuss the use of van der Waals (vdW) heterostructures to design new quantum materials. These heterostructures, made by assembling layers of two-dimensional materials together, offer a new way to create quantum matter and break through traditional material synthesis limitations.

I will present two examples of this approach. In the first example, I will illustrate how Coulomb interactions across separate atomic layers pair fermions (electrons and holes) into bosons to achieve a superfluid condensate state. Thanks to the tunability of the vdW platform, we can vary the pairing strength and change the nature of this fermion condensate from strong coupling to weak coupling, demonstrating a long-sought paradigm known as the BEC-BCS crossover. The second example will introduce the concept of moiré band engineering, where the interference between two atomic lattices reforms electronic band structures. In twisted double bilayer graphene, the moiré pattern creates highly degenerate electronic bands on which correlated electron states form. By using a perpendicular electric field to tune the electronic band structure, we can observe how the electron correlation evolves, providing insight into the nature and origins of these correlated states. Finally, I will briefly discuss applications of local probe techniques to uncover hidden quantum properties in vdW platforms and share visions of leveraging rich interplays across atomic interfaces to access major themes in condensed matter physics.

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