New phase boundary in highly correlated, barely metallic V2O3.

S. A. Carter, ' T. F. Rosenbaum, 3. M. Honig, and 3. Spalek "The James Franck Institute and Department of Chemistry, The Unicersity of Chicago, Chicago, Illinois 60637 'T-he James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637 "'Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 ' 'Department of Physics, Purdue University, West Lafayette, Indiana 47907 (Received 12 September 1991) %e compare the magnetic and transport properties of the low-temperature metal in nonstoichiometric and compressed vanadium sesquioxide. Antiferromagnetic order is robust for the full range of vanadium vacancy concentrations, but it can be suppressed with modest hydrostatic pressures. The temperaturepressure phase diagram for U203 thus includes a new T=O boundary between antiferromagnetic and paramagnetic metals. Furthermore, analysis of the T 0 diAusive metallic conductivity at the approach to the insulator-metal transition indicates a difIerent role for correlations depending upon the means employed to eAect the transition.