Spin-1/2 <i>Kagomé</i>-Like Lattice in Volborthite Cu₃V₂O₇(OH)₂·2H₂O

Abstract

A novel cuprate Volborthite, Cu3V2O7(OH)2-2H2O, containing an S-1/2 (Cu 2+\nspin) kagome-like lattice is studied by magnetic susceptibility, specific heat,\nand 51 V NMR measurements. Signs for neither long-range order nor spin-gapped\nsinglet ground states are detected down to 1.8 K, in spite of large\nantiferromagnetic couplings of ~100 K between Cu spins forming a\ntwo-dimensional kagome-like network. It is suggested that Volborthite\nrepresents a system close to a quantum critical point between classical\nlong-range ordered and quantum disordered phases.\n