Using electronic structure changes to map the H-T phase diagram of alpha '-NaV2O5 - art. no. 220401

We report polarized optical reflectance studies of alpha'-NaV2O5 as a funct ion of temperature (4-45 K) and magnetic field (0-60 T). Rung directed elec tronic structure changes, as measured by near-infrared reflectance ratios D eltaR(H)=R(H)/R(H=O T), are especially sensitive to the phase boundaries. W e employ these changes to map out an H-T phase diagram. Topological highlig hts include the observation of an additional phase boundary slightly below T-SG, enhanced curvature of the 34 K phase boundary above 35 T, and, surpri singly, strong hysteresis effects of both transitions with applied field.