Senlei Li - Thesis Dissertation Defense

In partial fulfillment of the requirements for the degree of 

Doctor of Philosophy in Physics

School of Physics Thesis Dissertation Defense

Senlei Li

Dr. Chunhui Rita Du, School of Physics, Georgia Institute of Technology (Advisor)

Multimodal Scanning-Probe Quantum Sensing of Quantum Materials

Thesis Committee: 

Dr. Zhigang Jiang, School of Physics, Georgia Institute of Technology
Dr. Itamar Kimchi, School of Physics, Georgia Institute of Technology
Dr. Hailong Wang, School of Physics, Georgia Institute of Technology
Dr. Bolei Deng, Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology

Abstract:

This dissertation develops scanning nitrogen-vacancy (NV) quantum sensing as a local probe of magnetic and superconducting quantum materials. Scanning NV microscopy is used to image magnetic domains and switching in Mn₃Sn, resolve stacking-dependent magnetic phases in twisted CrI₃, and probe coherent microwave fields, magnetic noise, and vortices in a superconducting Nb resonator. The technique is further applied to twisted Bi₂Sr₂CaCu₂O₈+x, where local magnetic and noise measurements reveal boundary- and field-dependent responses associated with unconventional superconductivity. Together, these studies demonstrate scanning NV microscopy as a versatile multimodal platform for connecting nanoscale electromagnetic signals with microscopic phenomena in quantum materials.