NMR/NQR studies of strongly correlated electron systems

We report on an intimate interplay between superconductivity (SC) and antiferromagnetism (AFM) in CeRhIn5 under pressure and multilayered high-Tc caprates via the NMR/NQR measurements. The experiments on CeRhIn5 has revealed that a first-order quantum phase transition (QPT) occurs around Pc∼2 GPa from the AFM to the paramagnetism in the superconducting regime and the novel superconducting nature in the coexistent phase of AFM and SC. The site selective Cu-NMR study demonstrated that the under-doped five-layered high-Tc cuprate, HgBa2Ca4Cu5O12+δ with Tc=72K can uniformly coexist on the microscopic level with the AFM. This is the first microscopic evidence for the uniform mixed phase of AFM and SC on a single CuO2 plane in a simple environment without any vortex lattice and/or stripe order. (author)