Abstract
AVO spinels provide a unique opportunity for studying the evolution of the charge gap of Mott insulators that approach the itinerant electron limit under the application of external pressure. Here we report high-pressure resistivity and optical measurements in ZnVO that provide unambiguous evidence of an unusual nonmonotonic behavior of the charge gap, , as a function of pressure . These unexpected results suggest that ZnVO undergoes a crossover from a Mott insulator with a charge gap dominated by the on-site Coulomb repulsion , to a second type of insulator in the high pressure regime. Our Monte Carlo simulations of the three-band Hubbard model relevant for ZnVO reproduce the nonmonotonic behavior of and provide a partial understanding of this exotic phenomenon.
- Received 11 May 2012
DOI:https://doi.org/10.1103/PhysRevB.86.020405
©2012 American Physical Society