Quantum phase transition induced by Dzyaloshinskii-Moriya interactions in the kagome antiferromagnet

We argue that the S=1/2 kagome antiferromagnet undergoes a quantum phase transition when the Dzyaloshinskii-Moriya coupling is increased. For D < D-c the system is in a moment-free phase, and for D>D-c the system develops antiferromagnetic long-range order. The quantum critical point is found to be D-c similar or equal to 0.1J using exact diagonalizations and finite-size scaling. This suggests that the kagome compound ZnCu3(OH)(6)Cl-3 may be in a quantum critical region controlled by this fixed point.