An approach has been made to deduce the second moment contribution of the planar Cu NMR line from indirect nuclear couplings, using the middle plane sites of the trilayer superconductor, Hg 0.8 Re 0.2 Ba 2 Ca 2 Cu 3 O 8 (T c ϭ126 K). We find that T 1 fluctuations of neighboring nuclear spins in the plane are the dominant causes of the spin-echo decay observed in the present case of an external field perpendicular to the c axis. Taking account of this effect in the analysis, the second moment is deduced. From the T dependences of the T 1 and second moment thus obtained, we find the dynamical exponent, zϭ2. The present result indicates that the boundary of z crossing from 2 ͑overdamped regime͒ to 1 ͑quantum critical regime͒ may be shifted more closely to the antiferromagnetic phase than previously assumed. It is also shown that the pseudogap is not a specific feature to the zϭ1 region. ͓S0163-1829͑99͒50922-3͔
RAPID COMMUNICATIONS
R14 170PRB 59 GOTO, SHIMIZU, SASTRY, AND SCHWARTZ 24 This is the expression for the systems with axial symmetry, and in the static limit.
RAPID COMMUNICATIONS
R14 172PRB 59 GOTO, SHIMIZU, SASTRY, AND SCHWARTZ