High field ESR measurements of S = 1/2 kagome heisenberg antiferromagnet ZnCu3(OH)6Cl2

We report the spin dynamics of the quantum kagome lattice ZnCu3(OH)6Cl2 observed by our high field ESR. The spin susceptibility deduced from our ESR result follows the Curie-Weiss-dependence, which is identical with the magnetic susceptibility. No resonance shift is observed down to 1.8 K in our measurement. This means that the internal field does not develop down to very low temperature. Moreover, the linewidth turns out to take the constant value from room temperature to 1.8 K. It suggests that the spin-spin correlation does not develop down to very low temperature of 0.009J. Our results suggest that ZnCu3(OH)6Cl2 looks like an ideal S = 1/2 kagome antiferromagnet from the ESR point of view.