  Extensive Cu-NMR studies on multilayered high-Tc cuprates have deduced the
following results;(1) Antiferromagnetic (AFM) moment M_{AFM} is decreased with
doping, regardless of the number of CuO_2 layers n, and collapses around a
carrier density N_h = 0.17. (2) The AFM ordering temperature is enhanced as the
out-of-plane coupling J_{out} increases with increasing n. (3) The in-plane
superexchange J_{in} is invariant with doping, but is even increased. (4) The
dome shape of T_c from the underdoped to the overdoped regime with a maximum
T_c at N_h = 0.22 does not depend on n, but its maximum value of T_c seems to
depend on n moderately. The present results strongly suggest that the AFM
interaction plays the vital role as the glue for the Cooper pairs, which will
lead us to a genuine understanding of why the T_c of cuprate superconductors is
so high.
