NUCLEAR-SPIN RELAXATION IN 2-DIMENSIONAL HEISENBERG-ANTIFERROMAGNET S=1 2 WITH SKYRMIONS/

The nuclear spin relaxation rate 1/T-1 is calculated for a two-dimensi onal quantum Heisenberg antiferromagnet S=1/2 with thermally excited s kyrmions at temperatures T less than or equal to J, where J is the nea rest-neighbor exchange constant. It is found that 1/T-1 first exponent ially decreases with increasing temperature, passes a minimum at T-min = 0.67J and then linearly increases before approaching its high-tempe rature limit. A comparison with calculations for a nonlinear sigma-mod el without skyrmions and experimental results is given. (C) 1998 Elsev ier Science Ltd. Al rights reserved.