SPIN DYNAMICS IN LA2-XSRXCUO4 (0.02-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.08) FROM LA-139 NQR RELAXATION - FLUCTUATIONS IN A FINITE-LENGTH-SCALE SYSTEM

La-139 NQR spin-lattice relaxation rates (NSLR) versus temperature are presented for La2-xSrxCuO4 with x=0.02-0.08. The NSLR below approximately 2T(N)(x) shows a power-law critical behavior while above approximately 2T(N)(x) it follows an exponential law with a small x-dependent spin-stiffness constant, where T(N)(x) is the magnetic ordering temperature. It is argued that the NSLR arises from fluctuations of the staggered magnetization in locally ordered mesoscopic domains. We infer that the magnetically ordered state is not a conventional spin glass, as is often assumed.