Investigating high temperature nickelate superconductivity through local stress and Meissner effect imaging using NV centers

Recent reports on signatures of high-temperature superconductivity in Ruddlesden-Popper (RP) Nickelates under pressure, with a critical temperature (Tc) near 80 K, have sparked great interest. By using a shallow layer of nitrogen-vacancy (NV) centers implanted directly within the diamond anvil applying the pressure, we show simultaneous evidence from both electrical transport and the Meissner effect of superconductivity of the single-crystal RP Nickelate La₃Ni₂O₇₋ₓ. Moreover, the micron scale spatial correlations between the diamagnetic response, local stress, and structural and chemical composition have been explored, offering insights into the origins of high-Tc superconductivity.