Low-dimensional spin S=1/2 system at the quantum critical limit:: Na2V3O7 -: art. no. 167202

We report the results of measurements of the dc susceptibility and the Na-23-NMR response of Na2V3O7, a recently synthesized, nonmetallic low dimensional spin system. Our results indicate that, upon reducing the temperature to below 100 K, the V4+ moments are gradually quenched, leaving only one moment out of nine active. The NMR data reveal a phase transition at very low temperatures. With decreasing applied field H, the critical temperature shifts towards T=0 K, suggesting that Na2V3O7 may be regarded as an insulator reaching a quantum critical point at H=0.