Nuclear relaxation rates in the herbertsmithite kagome antiferromagnets ZnCu3(OH)6Cl2

Local spectral functions and nuclear magnetic relaxation (NMR) rates, 1/T1, for the spin-half Heisenberg antiferromagnet on the Kagome lattice are calculated using the Moriyas Gaussian approximation, as well as through an extrapolation of multiple frequency moments. The temperature dependence of the calculated rates is compared with the oxygen 1/T1 NMR data in Herbertsmithite. We find that the Gaussian approximation for 1/T1 shows behavior …