Since the discovery of high-temperature superconductivity in cuprates by Bednorz and Müller, NMR has contributed notably to our view and understanding of cuprate chemistry and physics, of which a brief account is given here. However, recent major insights from NMR that, at least in part, challenge certain views developed in the early years of cuprate research will be our focus: (i) The failure of a single-component spin susceptibility to adequately describe NMR shift data may indicate the presence of more than one electronic fluid. (ii) NMR quadrupole splittings provide a quantitative measure of local charges in the CuO2 plane, and we find unexpectedly large differences between different cuprate families. These local charges, measured with NMR, appear to set the maximum Tc and the superfluid density. A phase diagram using these local Cu and O charges rather than the total doping per CuO2, gives a unified view of all cuprates and further insight can be expected if cuprate properties are discussed in this context. (iii) Based on magnetic field dependent and new pressure dependent NMR experiments, a review of NMR literature data, and the measurability of local charges with NMR, we argue that dynamic charge density variations are likely a universal phenomenon in cuprate superconductors.
Jurkutat, M., Kohlrautz, J., Reichardt, S., Erb, A., Williams, G. V. M., & Haase, J. (2017). NMR of cuprate superconductors: Recent developments. In Springer Series in Materials Science (Vol. 255, pp. 77–97). Springer Verlag. https://doi.org/10.1007/978-3-319-52675-1_8