Quantum Phase Transition Induced By Dzyaloshinskii-moriya Interactionsrnin The Kagome Antiferromagnet

摘要

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 approx=0.1J using exact diagonalizations and finite-size scaling. This suggests that the kagome compound ZnCu_3(OH)_6Cl_3 may be in a quantum critical region controlled by this fixed point.