Spin Waves in Random Spin Chains
arXiv:cond-mat/0208607 · doi:10.1063/1.1541640
Abstract
We study quantum spin-1/2 Heisenberg ferromagnetic chains with dilute, random antiferromagnetic impurity bonds with modified spin-wave theory. By describing thermal excitations in the language of spin waves, we successfully observe a low-temperature Curie susceptibility due to formation of large spin clusters first predicted by the real-space renormalization-group approach, as well as a crossover to a pure ferromagnetic spin chain behavior at intermediate and high temperatures. We compare our results of the modified spin-wave theory to quantum Monte Carlo simulations.
3 pages, 3 eps figures, submitted to the 47th Conference on Magnetism and Magnetic Materials