Spin-1/2 kagome-like lattice in Volborthite Cu3V2O7(OH)(2)center dot 2H2O

A novel cuprate Volborthite, Cu3V2O7(OH)(2). 2H(2)O, containing an S-1/2 (C u2+ spin) kagome-like lattice is studied by magnetic susceptibility, specif ic heat, and V-51 NMR measurements. Signs for neither long-range order nor spin-gapped singlet ground states are detected down to 1.8 X in spite of la rge antiferromagnetic couplings of similar to 100 K between Cu spins formin g a two-dimensional kagome-like network. It is suggested that Volborthite r epresents a system close to a quantum critical point between classical long -range ordered and quantum disordered phases.