UNIVERSAL MAGNETIC-PROPERTIES OF LA2-DELTA-SR-DELTA-CUO4 AT INTERMEDIATE TEMPERATURES

We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature (T) stiffness rho(s), but with the ratio k(B)T/rho(s) arbitrary. Universal scaling forms for the uniform susceptibility (chi(u)), correlation length (xi), and NMR relaxation rate (1/T1) are proposed and computed in a 1/N expansion and by Monte Carlo simulations. For large k(B)T/rho(s), chi(u)(T)/T and Txi(T) asymptote to universal values, while 1/T1(T) is nearly T independent. We find good quantitative agreement with experiments and some numerical studies on La2-deltaSrdeltaCuO4.