Towards a new interpretation of NMR and cuprate electronic properties*

Recently, for a number of different materials we established that a single spin component cannot explain the NMR shifts, pointing also to a different magnetic hyperfine scenario. Driven by these finding we compiled literature shift data for planar Cu, from which it becomes obvious, now, that the hitherto adopted interpretation of the NMR shifts is wrong, e.g., a large isotropic shift reigns on the strongly overdoped, Fermi liquid side of the phase diagram and starts disappearing as doping and/or temperature are lowered. Also recently, we showed that the charges in the CuO2 plane can be quantified with NMR, which, e.g., led to the discovery that the sharing of holes between Cu and O (not the doping) is responsible for various cuprate properties, e.g., their maximum Tc. In yet another set of experiments we solved a long-standing NMR conundrum that considered Y-1237 and Y-1248 to be very ‘homogeneous’ materials, while most other cuprates show large electric field variations in the plane. We find that these homogeneous systems are in fact highly charge ordered systems. This charge ordering that responds to pressure, temperature, and magnetic field is likely to be ubiquitous to the CuO2 plane as literature shows.