Local magnetic measurements of quantum materials

Magnetic moments and moving charges produce magnetic fields. Probing these stray magnetic fields on a local scale can provide a unique window into emergent phenomena in quantum materials. My lab is using and developing a variety of magnetic probes with a current focus on superconducting quantum interference devices (SQUIDs), Hall probes and nitrogen-vacancy centers in diamond. In this talk, I will review some of our recent work that uses these magnetic probes including imaging a spatially modulated superconducting transition in microstructures fabricated from a heavy-fermion superconductor, studying the current distribution and magnetization in a quantum anomalous Hall insulator and measuring the superfluid response of an atomically thin van der Waals superconductor. If time permits, I will discuss current limitations and frontiers in magnetic imaging and speculate how we may achieve higher spatial resolution and bandwidth and additional functionality.