ANOMALOUS LONG-TIME TAIL BEHAVIOR OF SPIN-SPIN CORRELATION IN THE NORMAL-STATE OF TL2BA2CUOY

We have found a frequency (omega) dependence of the spin-lattice relax ation time in the normal state of Tl2Ba2CuOy (T(c) = 15 and 85 K). The value of 1/T1T at the Tl and Cu sites is proportional to lnomega-1 at low temperature. This type of omega dependence suggests a long time t ail behavior of the spin-spin correlation. On the other hand, no frequ ency dependence is observed at the planar oxygen site; thus the observ ed long time tail behavior is enhanced around the wave vector q = (pi, pi). The characteristic cutoff frequency for the long time tail decre ases with decreasing T, indicating that the confinement of spin freedo m occurs above T(c).