Orbital-selective insulator-metal transition inV2O3under external pressure

Abstract

We present a detailed account of the physics of Vanadium sesquioxide (V2O3), a benchmark system for studying correlation induced metal-insulator transition(s). Based on a detailed perusal of a wide range of experimental data, we stress the importance of multi-orbital Coulomb interactions in concert with first-principles LDA bandstructure for a consistent understanding of the PI-PM MIT under pressure. Using LDA+DMFT, we show how the MIT is of the orbital selective type, driven by large changes in dynamical spectral weight in response to small changes in trigonal field splitting under pressure. Very good quantitative agreement with (i) the switch of orbital occupation and (ii) S = 1 at each V 3+ site across the MIT, and (iii) carrier effective mass in the PM phase, is obtained. Finally, using the LDA+DMFT solution, we have estimated screening induced renormalisation of the local, multi-orbital Coulomb interactions. Computation of the one-particle spectral function using these screened values is shown to be in excellent quantitative agreement with very recent experimental (PES and XAS) results. These findings provide strong support for an orbital-selective Mott transition in paramagnetic V2O3.

Metal–Insulator Transition in the Two-Orbital Hubbard Model at Fractional Band Fillings: Self-Energy Functional Approach

“…9,10) It is suggested that a Mott transition in some of relevant orbitals, i.e., an orbital selective Mott transition (OSMT), 11) is induced by the chemical substitution of Ca ions and also by the change in temperatures, where the heavy metallic state is realized. Furthermore, the pressure-induced OSMT is also suggested in the vanadium oxide V 2 O 3 , 12) which stimulates further theoretical and experimental 35,36) investigations on the effect of electron correlations in the system with orbital degeneracy.…”

Microscopic description of insulator-metal transition in high-pressure oxygen

“…The features are well understood as follows. In a multiband situation, Δ acts like an external “Zeeman” field 39, 43 in the orbital sector. The insulator-metal transition is characterized by a sudden jump in the renormalized δ z , and in the p x and p y populations as a consequence, suggesting that anisotropic structural (and volume) changes will accompany the orbital-selective Mott transtion.…”

Synthesis and characterization of V2O3 nanocrystals by plasma hydrogen reduction

“…shows a first order metal-insulator transition at about 150-160 K, with an accompanying several-order decrease in specific resistivity and changes in crystallographic symmetry, lattice constants and spin ordering [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The doping of a small amount of Al, Cr or W, Ti can shift the transition temperature to high or low region [8,[16][17][18][19][20].…”