Physics colloquium-“Atomically Resolved Studies of Unconventional Quantum Phases in 2D Materials and Heterostructures”

Yulia Maximenko

Colorado State University, Department of Physics

Abstract: The search for novel quantum phases in 2D materials is rapidly expanding: It is driven by the interest in robust quantum anomalous Hall insulators, topological superconductivity, correlated electronic states, and fractional statistics and by the prospect of quantum simulation in solid state. Unconventional, inherently quantum behavior has been observed in layered and twisted graphene heterostructures, multilayered homo- and heterobilayer transition metal dichalcogenides (TMDs), in surface and quasi-2D layers in 3D materials, and nanopatterned devices. To progress further, the field relies on tunable systems to study phase transitions and on atomic resolution to correlate the phases with local physical and electronic properties. In this colloquium, I will showcase recent developments in the field of tunable 2D platforms, highlighting twisted moiré systems, topological 2D materials, and atomic manipulation. Scanning tunneling microscopy (STM) has proved crucial for untangling competing quantum phases and deeply understanding the foundational elements driving their physics. Through high-resolution magnetic-field scanning tunneling spectroscopy, we have demonstrated the importance of the fine details of quantum geometry in these novel 2D platforms. Specifically, I will report on our discovery of the emergent anomalously large orbital magnetic susceptibility in twisted double bilayer graphene, along with the orbital magnetic moment. I will also discuss the potential in the field of quantum materials of combining STM, molecular beam epitaxy (MBE), and stacked 2D devices. As an example, I will present STM data on a back-gateable MBE-grown thin film of the quantum spin Hall insulator WTe₂.

Pre-seminar snacks will be offered in CoorsTek 140/150 from 3:30pm-4:00pm.