UNC Physics Colloquium

Yonglong Xie, Harvard University

Probing Quantum Materials with Scanning Probe Microscopy

Abstract
Electrons inside matter can behave as complex particles that do not exist in the Standard Model. These seemingly impossible effects are examples of emergent phenomena—that is, unexpected collective behavior—of electrons in quantum materials. The discovery and characterization of new emergent phenomena in quantum materials not only expand the boundary of our knowledge, but also provide unique opportunities for future quantum technologies. However, these effects often manifest in subtle ways, and thus detecting them requires developing new, more sophisticated measurement tools.

In this talk, I will demonstrate how a class of experimental techniques called scanning probe microscopy can be a general tool for unlocking new phenomena in quantum materials. To illustrate the power of this approach, I will focus on our recent experimental observation of novel topological quantum states in magic-angle graphene, enabled by scanning single-electron-transistor microscopy. In addition, I will highlight other examples in which scanning probe microscopy permits the discovery of novel phases in other quantum materials. Finally, I will conclude by outlining how pushing the boundaries of existing scanning probe microscopy will enable the discovery and characterization of new emergent phenomena and functionalities in quantum materials, devices, and circuits.