Prabudhya Bhattacharyya, UC Berkeley

Imaging magnetism in superhydrides at megabar pressures using nanoscale quantum sensor

Tuning pressure near megabar (100 GPa) regimes presents an exciting frontier in the exploration of novel condensed phases. However, large stress gradients and small sample sizes can constrain the use of conventional probes for materials characterization in these extreme environments. The use of Nitrogen Vacancy (NV) color centers in diamond presents a promising platform for in situ metrology in DACs with high sensitivity and diffraction limited sub-micron spatial resolution. In this talk, I will detail our work on pushing NV based quantum sensing up to megabar pressures. By engineering the projection of the anvil stress on the NV centers, we overcome contrast loss and demonstrate continuous-wave and pulsed measurements up to ~ 140 GPa. I will also share our recent work on probing superconductivity in a cerium superhydride (CeH₉) through simultaneous transport and NV measurements. On zero field cooling, we measure a spatially resolved diamagnetic response in this material. On field cooling, we observe a trapping of the magnetic flux on the sample. On sweeping temperature, we find concurrent transitions in both magnetism and transport resistance that are consistent with superconductivity.