Quantum Sensing of Layered Superconductor at the Nanoscale

We introduce single spin magnetometry based on nitrogen-vacancy (NV) centers in diamond as a new platform to probe the microwave response of a two-dimensional layered high Tc superconductor Bi₂Sr₂CaCu₂O_8+x (BSCCO) flake at the nanoscale. We observed a temperature-dependent spatial profile of the microwave field around the BSCCO flake, which can be attributed to the variation of the conductivity in BSCCO. Our technique provides a novel method to characterize the superconducting phase transitions without making electrical contacts and opens up new possibilities for nanoscale imaging of the charge dynamics in layered materials.