Nonmonotonic evolution of the charge gap in ZnV2O4 under pressure

A2+V2O4 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 ZnV2O4 that provide unambiguous evidence of an unusual nonmonotonic behavior of the charge gap, , as a function of pressure P. These unexpected results suggest that ZnV2O4 undergoes a crossover from a Mott insulator with a charge gap dominated by the on-site Coulomb repulsion U, to a second type of insulator in the high pressure regime. Our Monte Carlo simulations of the three-band Hubbard model relevant for ZnV2O4 reproduce the nonmonotonic behavior of (P) and provide a partial understanding of this exotic phenomenonWe acknowledge financial support from the DFG (SFB 484 and SFB 608) and the Bayerische Forschungsstiftung. F.R. acknowledges support from Ministerio de Economa y Competitividad, Spain, through the project MAT2010-16157. Work at LANL was performed under the auspices of the US DOE Contract No. DE-AC52-06NA25396 through the LDRD programS

Pressure-induced quantum phase transition in Fe₁−ᵪCoᵪSi (x = 0.1,0.2)

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Pressure-induced quantum phase transition in Fe1−xCoxSi (x = 0.1, 0.2)

Please read abstract in the article.This work was financially supported by the Deutsche Forschungsgemeinschaft (DFG) through SFB 608 and a joint project of DFG and the South African National Research Foundation (NRF). M.K.F. and M.M.A. thank A. Rosch and E. Bauer for fruitful discussions