Nanoscale quantum sensing of quantum materials through a single spin magnetometer

We introduce single spin magnetometry based on nitrogen-vacancy (NV) centers in diamond as a new measurement platform to locally probe the magnetic properties of quantum materials with a nanoscale spatial resolution. Utilizing this measurement platform, we have demonstrated control and local measurements of spin chemical potential in a magnetic insulator yttrium iron garnet (YIG) at the ambient condition, which opens up new possibilities for nanoscale imaging of spin-related phenomena. In additional, we investigate the temperature-dependent microwave response of an exfoliated high-T_c superconductor Bi₂Sr₂CaCu₂O_8+x (BSCCO) flake, from which the superconducting phase transition and penetration depth can be obtained in a non-invasive fashion. Our results demonstrate the unique capability enabled by NV spin magnetometry in exploring the exotic local spin and charge behavior of emergent material systems.