  We report systematic Cu- and F-NMR measurements of five-layered high-Tc
cuprates Ba2Ca4Cu5O10(F,O)2. It is revealed that antiferromagnetism (AFM)
uniformly coexists with superconductivity (SC) in underdoped regions, and that
the critical hole density pc for AFM is ~ 0.11 in the five-layered compound. We
present the layer-number dependence of AFM and SC phase diagrams in hole-doped
cuprates, where pc for n-layered compounds, pc(n), increases from pc(1) ~ 0.02
in LSCO or pc(2) ~ 0.05 in YBCO to pc(5) ~ 0.11. The variation of pc(n) is
attributed to interlayer magnetic coupling, which becomes stronger with
increasing n. In addition, we focus on the ground-state phase diagram of CuO2
planes, where AFM metallic states in slightly doped Mott insulators change into
the uniformly mixed phase of AFM and SC and into simple d-wave SC states. The
maximum Tc exists just outside the quantum critical hole density, at which AFM
moments on a CuO2 plane collapse at the ground state, indicating an intimate
relationship between AFM and SC. These characteristics of the ground state are
accounted for by the Mott physics based on the t-J model; the attractive
interaction of high-Tc SC, which raises Tc as high as 160 K, is an in-plane
superexchange interaction Jin (~ 0.12 eV), and the large Jin binds electrons of
opposite spins between neighboring sites. It is the Coulomb repulsive
interaction U ~ (> 6 eV) between Cu-3d electrons that plays a central role in
the physics behind high-Tc phenomena.
